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MLR: Electrical Study Guide

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1. 20 Yellow Blade Style Fusa 30 Light Green 40 Orange or Amber Blue Circuit Breakers Unlike fuses circuit breakers can be reset either manually or automatically and reused Circuit breakers are either cycling or ISU Er aker non cycling Circuit breakers can be either cycling or non cycling Page 36 of 88 MLR Electrical Study Guide 2013 Melior Inc A circuit breaker is made with a bi metallic strip that operates much like the thermostat in many homes As current passes through the strip it creates heat which causes the two metals to expand but at different rates When one expands faster than the other the strip bends and opens a contact which stops current flow through the circuit In a cycling type of breaker the bi metallic strip will cool after the current stops and return to its original shape which closes the circuit to current flow once again A mechanical turn signal flasher works this way also A non cycling type of breaker will open from excessive current as well but must be manually reset Another type of circuit breaker is the solid state device called a PTC Positive Temperature Coefficient PTCs have no moving parts and are commonly used in window motors and door lock actuators to protect the circuit from damage should a control switch become stuck or in case a limit switch fails They can also be used as end of travel stops without a limit switch Power Window Schemati
2. Waveforms This is a typical normal output waveform The alternator is Normal Waveform charging correctly Cee tree nee This waveform is also normal but indicates the alternator Waveform Under Heavy Load is under a heavy load WIV This pattern is seen with some charging systems that use Waveform with Inductive Spikes electronic regulators and duty cycles The higher inductive NAAM spike is normal on these systems This pattern shows a duty cycle from a control module to Duty Cycle Waveform to Field Windings the field windings Page 86 of 88 MLR Electrical Study Guide 2013 Melior Inc This is an unacceptable waveform The high spikes in this Open Diode Waveform pattern indicate an open diode This unacceptable waveform is showing one open diode Waveform of Open and Shorted Diodes and one shorted diode a This waveform also unacceptable shows shorted diodes Waveform Showing Shorted Diodes or or stator windings Stator Windings PAA TAAA TA TAAT LAAT IAAT LAAT MAAT MAAT had Tests Charging System Output Test The load testers used for checking batteries and starting systems also provide an effective means for testing charging systems They can test for adequate current and voltage output under varying loads up to the rated capacity of the generator Load testers also have features for testing alternator diodes and stator windings In general the procedure consists of the following e Connect the
3. Wires and Cables When checking wiring ensure the following conditions are met e Cables are routed to avoid heat abrasion and vibration Connection Points e Grommets are in place where cable passes through holes in When testing an electrical circuit sheet metal never pierce an electrical wire with e Insulation is intact any type of probe Doing so will allow e Cables are supported every 24 inches moisture to enter the circuit causing e A strain relief or anchor point is provided a short distance corrosion and high resistance Always test circuits at connection points from the battery terminal Keep in mind that the longer a cable is the more voltage drop will occur Be sure adequate sized cable is used For example a cable 22 feet long that is required to carry 150 amps should be 00 AWG which has a conductor approximately 3 8 of an inch in diameter Rope stranded core is recommended Cable gauge must be sufficient to prevent voltage drop from exceeding the following SAE specifications e 6volt light and medium duty 12 volts per 100 amps e 12 volt heavy duty 12 volts per 100 amps e 12 volt light and medium duty 20 volts per 100 amps e 24 and 32 volt heavy duty 20 volts per 100 amps e 24 volt light and medium duty 40 volts per 100 amps e 12 volt high output heavy duty 075 volts per 100 amps e 12 volt super heavy duty 060 volts per 100 amps Minimum gauge size for 12 volt high output systems mu
4. 2013 Melior Inc Heater Element Aai Psi Typical Headlight Bulb Heater elements are used in several different places on modern Heater Element automobiles Some of the more common places are e Seats heated seats e Rear window defrosters e Cigar lighters e Oxygen sensors DC Motor In modern automobiles DC motors are used to move seats raise and lower windows control engine idle speed and perform many other functions throughout the vehicle Rubber Grommet Rubber grommets are used to protect electrical wires going through the bulkhead or other places where there is a possibility of insulation damage that could cause a short circuit A rubber grommet can be helpful when using a wiring diagram for location purposes The darker black section of the grommet indicates the area going away from the passenger compartment The lighter area of the grommet is inside the passenger compartment Horn A horn is a safety warning device Most modern vehicles are equipped with two horns one high note and one low note Heated Seat Motor Symbol _ Motor Rubber Grommet Rubber Grommet Symbol o Horn Symbol Horn Page 18 of 88 MILR Electrical Study Guide 2013 Melior Inc Wiring Diagrams In an electrical diagram it s important to become familiar with connectors splices and ground locations The following is a typical section of a wiring diagram Please take t
5. Fusible Link Grounds Ground reference is a common reference point for electrical electronic circuits where electrical measurements can be taken ije Ground Symbol Ground is a common point in an electrical circuit connected to the negative side of the power supply It s not uncommon for more than one component to share a ground connection The ground provides the return path to the power source for the circuit all circuits must have a ground A ground return can be either hard wired to the battery negative or chassis grounded through the metal pieces of the vehicle Case grounded components have an internal connection to their metal Case Ground casing and become chassis grounded when installed in the vehicle Symbol K Typical Ground Switches Electrical switches are used to control current flow in an electrical circuit An electrical switch can be either normally open or normally closed depending on the type of circuit it s controlling Switches can be controlled by hydraulic pressure heat vacuum and even light Switches come in several different shapes and sizes When replacing an electrical switch you must ensure you are using one that can handle the circuit amperage The symbols and diagrams pictured here are common with most manufacturers Switches can appear in several different shapes and sizes Another type of switch is a momentary switch such as a horn or brake light switch Single Pole Single Throw Single Po
6. MLR Electrical Study Guide 2013 Melior Inc Electromagnets Electromagnetism occurs when an electrical current is passed through a conductor and creates a surrounding magnetic field Electromagnets usually consist of a wire wound around a metal core and powered by an electrical source Some students may have done an experiment in school where a wire was wrapped around a nail with both wire ends attached to a battery to form an electromagnet The device could then be used to pick up paper clips Examples of electromagnetic automotive applications include starter solenoids and fuel injectors as mentioned earlier as well as some EGR valves relay contacts transmission shift and pressure control solenoids numerous vacuum control valves blower motors cooling fans wiper motors fuel pumps generators and of course old style starter motors Magnetic Fields All magnets whether permanent or electromagnet have two poles North and South Like poles N N or S S repel and unlike poles N S attract Magnetic Field Automotive applications all operate by magnetic attraction rather than magnetic repulsion Between these two poles are The stronger a magnet is the invisible lines of force called the flux lines which make up the greater its flux density magnetic field A magnet with many flux lines or high flux density is strong whereas a weak magnet has few flux lines or low flux density Students may be familiar with in
7. formula we obtain e P IxE e P 10Ax120V e P 1200 Watts Left Rear Park Light Right Rear Park Lignt General Rules of Electricity Using our study of Ohm s law we can see that the relationships between voltage current and resistance follow general rules Resistance If the resistance remains the same e As voltage increases current increases e As voltage decreases current decreases Page 13 of 88 MLR Electrical Study Guide 2013 Melior Inc Voltage If the voltage remains the same e As resistance increases current decreases e As resistance decreases current increases Voltage Drop Voltage drop is a term that may be unfamiliar to new technicians but it will be very important in the diagnosis of electrical circuits To explain voltage drop let s return to our water hose analogy once again At one time or another we ve all folded a hose in half to stop the water flow so we could relocate a sprinkler or as a joke to someone trying to wash their car When that happens the water pressure remains the same between the kink in the hose and the faucet while the pressure on the other side of the kink is zero or almost zero This difference is called the pressure drop and it is principally the same as in electrical applications Voltage drop is then defined as the difference between the voltage on the inlet side of a device compared to the voltage on the outlet side Comparing that value to a written specification will
8. point B because the test light Is connected after the open In the circuit Point B TEST LIGHT Page 42 of 88 MLR Electrical Study Guide 2013 Melior Inc Short Circuit Grounded Circuit In this circuit the test light is being used to help diagnose a short circuit In this case the test light will illuminate until the short circuit is located and repaired In this circult the test light Is being used to diagnose a grounded circult If the test light and circult being tested have the same approximate resistance both will Illuminate However they will bo be dimmer than normal NOTE To perform this test the test light must be connceted in series with the circuit b Point of short circuit Hybrid System Identification Inspection and Precautions All hybrid vehicles have two power sources One is usually a gasoline power engine however some manufactures are planning to replace the gasoline engine with a small diesel engine Hybrid vehicle are also equipped with an electric engine Manufactures have developed several different configurations for hybrid vehicles Most can be classified as either series hybrid or parallel hybrid Both series and parallel hybrid vehicles operated using high voltage batteries and charging systems For that reason precaution must be taken when servicing or repairing hybrid vehicles High voltage wiring is bright orange in color Precaution
9. with an applied current but now we will find that we can also SAT L ee produce a current from a magnetic field The process is called Electromagnetic induction occurs electromagnetic induction When a magnetic field and a when a varying magnetic field creates wire are moved near each other a voltage is produced in the a current in a second winding wire that causes a current to flow This is called an Induced Voltage As long as the movement continues the current will continue but if the motion stops the current will stop Applications of electromagnetic induction are typically in generators or alternators and in transformers or ignition coils Generators and alternators are designed similarly to motors in that they have a field winding and an armature winding How they differ in terms of their induction is this generators have a coil that turns and a magnetic field that is stationary whereas alternators have a magnetic field turning inside of a stationary coil The amount of induced voltage and therefore current depends on several factors e Strength of the magnetic field e Speed of motion between the coil and the magnetic field e Number of conductors in the coil Chapter 2 Magnetic Components Let s take a few moments to cover some specific applications of electromagnetism relays solenoids motors and transformers Relays A relay is an electromagnetic device that operates as an on off switch using a small coil cu
10. Circuit In the series circuit to the right we have R 12 ohms lamp 1 resistance 8 ohms lamp 2 resistance 4 ohms l 1 amp 12 volts 12 ohms E 12 volts source voltage total i i are Here is where things get tricky Remember What is the voltage drop at Lamp 1 1 amp x 8 ohms 8 volts In a series circuit amperage remains the same throughout the circuit What is the voltage drop at Lamp 2 1 amp x 4 ohms 4 volts In the parallel circuit to the right using the same lamps as the series ao cece circuit above we have 4 ohms x 8 ohms Rr 4 ohms 8 ohms 2 6 ohms l 12 volts 2 6 ohms 4 5 amps 8 Ohms scams 3 E 12 volts source voltage total Can you determine the following Remember What is the current flow through Lamp 1 12 volts 8 ohms 1 5 amps In a parallel circuit voltage remains the same across each branch What is the current flow through Lamp 2 12 volts 4 ohms 3 amps Page 23 of 88 MLR Electrical Study Guide 2013 Melior Inc From the equations used above you can see that current flow through Lamp 1 and Lamp 2 equaled total amperage You can also see amperage is different through each lamp Current is less in Lamp 1 because its resistance is greater than that of Lamp 2 Chapter 3 Digital Multimeters Digital Multimeters In order for a technician to diagnose an electrical problem he must first test the system to determin
11. Float i Reading Below 1 100 Cell Reading 1 265 Keep in mind that hydrometer testing must be done while correcting for outside temperature Hydrometer Pickup Tube Electrolyte Temperature 40 F Hydrometer Reading 1 250 Subtract Specific Gravity 0 016 Corrected Specific Gravity Equals 1 234 Example Electrolyte Temperature 100 F Hydrometer Reading 1 240 Add Specific Gravity 0 008 Corrected Specific Gravity Equals 1 248 A Fully Charged Battery Has a Specific Gravity of 1 270 71 C 180 F it 032 65 5 G150 F H H 028 60 C 140 F F 024 54 5 C 130 F i H 020 49 C 120 F i 016 43 C 110 F H J 012 37 5 C 100 F j H 008 2 5 C 90 F j H 004 a7 G 80 F HH 000 21 C 70 F HH 004 5 155 C 60 F HH 008 a 19 C 50 F f H 012 45C 40 F j H 016 T O 30 F h O 020 85C 20 F HH 024 12 C 10 F HH 028 Hydrometer and Temperature Correction Page 59 of 88 MLR Electrical Study Guide 2013 Melior Inc Chapter 3 Charging and Replacement Load Testing Load testing a battery is an effective way to test the Charging Before Testing battery s actual performance ability To perform a load test a specified current load is applied to the battery For a load test to produce an accurate while its voltage is monitored If a battery s voltage drops result
12. SILVER divide by 100 Designates tolerance in S64S65h 44646 EXAMPLES RED RED BRN GLO 220 N 5 RED RED GLO 2 2 N 20 Page 38 of 88 MILR Electrical Study Guide 2013 Melior Inc Some resistors such as those found in blower motor circuits are wire Blower Motor Resistors 12 V 12 V wound and have no color bands as shown here Resistive values for ee eg oO a 5 B those should be printed in service ae manuals i I E E GE PE Resistors Relay Just as they have an Ohms value resistors also have a wattage value Common Recall from Module 2 that wattage Power is the product of Voltage Sizes and Current given by P IxE As such resistors are not rated in either l _ MOWAT voltage or current but rather in watts to limit their heat exposure For example if a resistor is rated at 10 Watts and is used in a 12 Volt 4 watr circuit then the maximum allowable amperage is 833 Amps I P E If we decrease the voltage by half to 6 volts then the current can w2 WAT double without damaging the resistor P IxE or P 1 66 amps x 6 volts or P 10 watts Most often the wattage rating of a resistor is a m determined by its size Some of the most common sizes are shown in PETAR the illustration Circuit Failure Opens Shorts and Grounds Electrical circuits can fail in several different ways The most common types of failures are open circuits short
13. a Step down will cause a lower voltage Your local electrical sub station has a series of Step down transformers to reduce the voltage before it enters your house IGNITION L TO SPARK PLUGS Transformers Page 8 of 88 MLR Electrical Study Guide 2013 Melior Inc The Step up or Step down ratio is determined by the number of turns of the wire used in both the primary and secondary windings One other thing to keep in mind is that the primary and secondary currents will also change except they go up as voltages drop and decrease as voltages increase As an example let s use the most common transformer in automotive use the ignition coil In a typical ignition coil the ignition module will apply 12 Volts pulsating DC with a current of between 4 10 Amps We ll use 6A as an example The voltage that comes from the secondary to fire the spark plugs is typically between 5 000 Volts and 20 000 Volts some can go as high as 80 000 Volts Our example will use 12 000 V If the input voltage is 12 Volts and the output voltage is 12 000 Volts then the step up ratio is 1000 1 12 000 12 while at the same time the current will drop by the same ratio from 6A to 006 Amps 6 1000 A Step down transformer will likewise increase the output current by the same ratio that the voltage was decreased It s also interesting to note that the input power and the output power for a transformer are basically identical Chapter 3 Electrical Pr
14. adjust the charging rate The switches are adjusted to obtain the desired voltage and the ammeter reading indicates the amount of current being accepted by the charging line To charge batteries in parallel Keep in mind that even if the charger is turned off any batteries connected to the bus bars are Connect all the batteries to the buss bars positive terminals Parallel Charging to the positive bar and negative terminals to the negative bar as shown Connect the charger to a power source and turn it on Adjust the voltage to the desired setting between 14 2 and 15 5 volts Monitor each battery every hour or two Disconnect any recharged battery It is not necessary to turn off the charger as long as there is at least one battery on the line but the line voltage will increase as batteries are removed so it may need to be reduced Bus Bar Clamps Storage and Precautions connected electrically and the line contains the If the bus bar clamps are normally clamped to amperage potential of all of the batteries their bus bar when not in use double check for combined proper polarity before returning them to the bus bar Crossing the polarity of the clamps will Jump Starting cause a fire and possible explosion Observe all safety precautions when jump starting To jump start a vehicle 1 Set the parking brake in both vehicles and place the transmission in Park if the vehicle has an automatic transmission or Neutr
15. and negative plates trapping the oxygen and sulfur and leaving water molecules behind left side of illustration The voltage potential of a battery is dependent on the dissimilarity of the active materials in the positive and negative plates As the lead sulfate content in the plates increases the voltage and available current decreases This process is reversed to charge the DISCHARGING BATTERY CHARGING BATTERY battery Current appli ed to th e batte ry POSITIVE ELECTROLYTE NEGATIVE POSITIVE ELECTROLYTE NEGATIVE PLATE PLATE PLATE causes the lead sulfate residing on the plates to release its oxygen into the a electrolyte This release increases the Gos Q acid content of the electrolyte and y lo returns the plates to their original compositions right side of illustration NE Page 48 of 88 MLR Electrical Study Guide 2013 Melior Inc Battery Safety There are important safety concerns to keep in mind when working on or around automotive batteries Batteries can explode and have enough power to arc weld Always respect the power of a battery even a dead battery The sulfuric acid in electrolyte is extremely corrosive and can cause severe chemical burns to the skin and eyes It will also damage painted surfaces and many other materials including clothing Always wear approved safety glasses when working around batteries and the use of rubber gloves is recommended when working with electrolyte You shoul
16. battery The plates in these batteries tend to be slightly shorter readily apparent that the cell covers are removable so check carefully to allow them to be submerged deeper in electrolyte Some maintenance free batteries do not have removable covers or caps Top Post Battery Others do to allow for the addition of water in case of overcharging or With Vent Caps Removed severe conditions and to permit hydrometer testing These batteries oe should not require additional water but if the electrolyte can be checked it should be checked approximately every six months Gel Cell and Absorbent Glass Mat AGM Batteries Recent innovations in battery technology include gel cell and absorbent glass mat designs These designs do not have free electrolyte Gel cell batteries were developed for use in mining equipment and have good resistance to shock and vibration In AGM batteries the elements are compressed The plates are thinner allowing for more plates per cell They are heat resistant and may last three times longer than wet cell batteries The gel cell and AGM designs have not yet seen widespread usage due to their higher cost Page 47 of 88 MLR Electrical Study Guide 2013 Melior Inc Electrolyte and Specific Gravity Specific gravity is a measure of the density or weight of a fluid using water as a baseline Water has a specific gravity of 1 000 and pure sulfuric acid has a specific gravity of 1 835 meaning it
17. car The table shows examples of typical parasitic draws measured in milliamps mA for various automotive components Component Typical Milliamp mA Draw Adapative Lamp Motor Blower Control Module ELC After 7 Minute Time Out O to 1 0 max Electronic Brake amp Traction Control Module 1 0 After 4 Minute Time Out Generator Heated Seat Control Module LH RH HVAC Programmer Instrument Panel Digital Cluster Gages Cluster Lamp Control Module Oil Level Module C Pull Down Unit RAC Module O to 3 8 max Retained Accessory Power Illuminated Entry Remote Keyless Entry Page 53 of 88 MLR Electrical Study Guide 2013 Melior Inc Parasitic draw can be measured by connecting an ammeter in series with the battery or by using an ammeter with an inductive pickup that closes around a battery cable All of the leads going to the battery terminal must be enclosed in the probe The inductive amps probe on starting and charging test equipment is typically accurate to only about 1 amps so in most cases an ammeter in series accurate in the milliamps range is needed Current draw from 5 to 30 milliamps is usually considered normal parasitic draw however some RV applications may have a normal parasitic load of up to 60 milliamps To properly test for parasitic loads with an ammeter connected in series requires a special tool The tool maintains continuity through the system until you are ready to take the re
18. circuit and preventing current flow Some circuit breakers must be reset manually Other circuit breakers reset automatically these are referred to as cycling circuit breakers Circuit Breaker Symbol An electronic circuit breaker will open and close automatically when the rated amperage is exceeded Electronic circuit breakers can be used to control power window circuits and other similar circuits Mechanical Circuit Electronic Circuit Breaker Breaker Fuses A fuse is another protection device Fuses are rated in amps and the rating is determined according to the maximum amount of current the circuit is designed to safely handle Fuses are always placed in series with the load device they are protecting A fuse is designed to open internally blow whenever current flow exceeds its rated value Fuse Symbol CAUTION Never replace a fuse with one of a higher amperage rating for the circuit or serious circuit damage or electrical fire could result Good Bad Good and Bad Fuses Fusible Links Another type of electrical protection device is fusible link wire Fusible link wire works similarly to a fuse Most fusible link wire is used with circuits that requires 30 amps or more Fusible Link Page 15 of 88 MLR Electrical Study Guide 2013 Melior Inc Symbol CAUTION Never replace fusible link wire with regular electrical wire Fusible link wire will open internally without burning the outer insulation
19. contribute to the discharging or weakening of a battery These factors may include e Normal aging e Overcharging or undercharging e Parasitic loads and phantom drains e Self discharging e Inoperative or missing hold downs e Normal Aging Any lead acid battery will eventually wear out due to Testing New Batteries normal cycling overcharging and undercharging l l Load testing a new battery at its rated A new battery that has never been in service has not yet capacity may result in false test failures developed its full power potential although normal cycling soon brings the battery to its capacity Page 51 of 88 MLR Electrical Study Guide 2013 Melior Inc The voltage difference between cells in a new battery is zero or negligible As a battery ages the voltage difference increases When the voltage difference reaches 05 volts the battery must be replaced The cell with the lowest voltage will drain the other cells Years of cycling will finally take their toll on any battery Small amounts of the active material on the positive plates are shed during cycling and fall to the bottom of the battery If the sediment at the bottom of the battery builds up enough to bridge the positive plates to the negative plates a shorted cell will result Overcharging Overcharging either by the vehicle s charging system or an external battery charger speeds the shedding of plate materials shortening battery life Ex
20. electrons past a certain point the greater the current or amperage Automotive systems vary from very high to very low current For instance the starter system typically is high current being in excess of 100 Amps whereas spark plug current is very low many confuse high voltage with high current in ignition coils at much less than one amp Current is generally referred to in one of two terms e Amperes Amperage Amps or A e Intensity or For our purposes A and I will be used interchangeably Conventional Current Flow vs Electron Current Flow There are two different ways to look at current flow in a complete circuit one is called Electron Flow and the other is Conventional Flow An understanding of the difference will help the technician in the use of electrical diagrams The Electron flow theory says that since electrons do the work in a circuit and since electrons have a negative charge then current must flow from the negative battery terminal through the circuit and into the positive terminal This is used mostly by electrical engineers Page 10 of 88 MLR Electrical Study Guide 2013 Melior Inc Conventional flow theory says that since positive is greater than negative then current must travel from to Conventional flow is used by the automotive and other industries DC and AC The current in any circuit will be one of two types Direct Current DC or Alternating Current AC Types of C
21. entire starting circuit If the battery is known to be in good condition and excessive voltage drop is indicated proceed to test the circuit components To check the voltage drop of the positive battery cable measure the drop from the positive battery terminal to the battery terminal on the solenoid while cranking with the fuel system disabled The reading indicates the voltage drop The rest of the circuit can be checked in a like manner Page 73 of 88 MLR Electrical Study Guide 2013 Melior Inc The illustration shows Checking Voltage Drop meter connections for all three of the common voltage drop tests If you use the starting and charging system tester s external volts leads the load clamps must be connected to the battery to power the meter s display In general a 2 voltage drop is acceptable for each Cranking the Engine cable or the solenoid If a higher voltage drop is indicated clean the connections and retest If the Do not crank the engine for more than 30 voltage drop is still high replace the component seconds at a time Five to ten seconds should be Starter relays and other small components are adequate to obtain the reading generally allowed a voltage drop of 2 volts Total starting system voltage drop should not normally exceed 6 volts No Load Test When removed from the vehicle the starter can be no load or bench tested First attempt to turn the Important Safety Precautions pini
22. is 1 835 times heavier than water Electrolyte contains 64 water and 36 acid which gives it a specific gravity of 1 265 to 1 270 in a fully charged battery this is often expressed as twelve seventy etc If the electrolyte is accessible it can be checked with a hydrometer As a battery is discharged the electrolyte contains less acid and more water so a hydrometer float will not rise as high in the hydrometer barrel or fewer balls will float Many maintenance free batteries have a hydrometer built into one of the cells We will cover those and hydrometer testing later in the section For now keep in mind that the acid is heavier than water and a discharged battery has more water in its electrolyte _ ll 64 Water 36 Acid SP GR 1 000 SP GR 1 835 Chemical Reactions while Discharging and Charging Electrolyte SP GR 1 265 In a fully charged battery the active materials in the positive and negative plates is distinctly different in chemical composition and the electrolyte has a high acid content Positive plates contain a compound of lead and oxygen PbO2 while negative plates contain lead Pb The electrolyte is composed of water H20 and sulfuric acid H2S04 Sulfuric acid is a compound of hydrogen sulfur and oxygen As a battery begins to discharge the composition of the plates becomes more similar and the water content of the electrolyte increases Lead sulfate PbSO4 is formed on both the positive
23. lf current decreases and resistance remains the same voltage will decrease Indirectly Proportional means that as one variable increases another variable will decrease in proportion e As resistance increases and voltage remains the same current will decrease e If resistance decreases and voltage remains the same current will increase Ohm s Law Solving Circle If memorizing formulas isn t your favorite thing to do then memorize and use the solving circle below All you need to do is cover the letter for the value you don t know and the formula to use will be shown by the remaining two For example If you want to know the voltage drop in a circuit just cover the letter E which will leave IxR Covering the I will give E R and if R is covered then E I remains Page 20 of 88 MLR Electrical Study Guide 2013 Melior Inc If you don t have the solving circle handy and can t remember the positions just remember the old mnemonic device Eagles flying over Indians chasing Rabbits It s a little silly but hard to forget Another is Victory over Automotive Repair Volts over Amps and Resistance Circuit Elements Before we can learn how to apply Ohm s law in a practical setting we must first have an understanding of some basic circuit elements Source The first requirement for any circuit is a source of power Automotive applications generally have two primary power sources the battery and
24. pull in winding failure will prevent the pinion from engaging at all On some starters a pull in winding failure will allow the motor to run even if the pinion is not engaged Reduction Starters On some starters called reduction starters extra gears are used to achieve even more reduction and develop higher torque A planetary gearset or an idler gear arrangement provides the additional gear reduction PINION PLANETARY GEAR CARRIER ARMATURE RING GEAR STATIONARY Page 69 of 88 MLR Electrical Study Guide 2013 Melior Inc Starting Circuit In a typical starting circuit the ignition switch is powered from a battery junction block and protected by a fusible link When the ignition switch is turned to the start position a current of less than 10 amps travels through a fuse The current then flows through the park neutral position and back up lamp switch PNP Proved the switch is in the park or neutral position The PNP is a safety feature to prevent cranking with the vehicle in gear Manual transmission equipped vehicles have a clutch petal position or CPP switch From the PNP switch current flows through the starter relay coil and to ground Energizing the relay coil causes the contacts to close supplying current from the junction block to the solenoid The hot at all times portions of the relay and solenoid circuits are protected with fusible links Energizing the solenoid causes the plunger to move
25. recharge the vehicle Under age batterier become mead et en i F no k nm i heavy acceleration both the electrical and sda heat ak gaapiia r gasoline operate ES i ilia service plug while Parallel hybrid vehicles starting of the vehicle maximum fuel and emis i WARNING Anytime sion effeciency i the vehicle is in the i READY mode the Servicing any part of the i Hig 3 gt 5 me engine may start age service plug In most cases the service plug is located at the High Volt age battery pack Both series and parallel hybrid system use two electrical systems A low voltage system is used to operate the tradition electrical system such as the lighting power window wipers and entertainment system The high voltage system is used to drive the vehicle Servicing the battery pack on hybrid vehicles must be done with caution Hybrid vehicle use device called an inverter to convert high voltage DC to High voltage AC Many late model hybrid electrical operate at voltage over 600 volts Because of the high voltages involved Basic safety precautions must be followed when servicing or inspecting any hybrid electrical system e Always wear rubber gloves rated to handle high voltage e Wear safety goggles e Wear rubber soled shoes safety shoes e Wear a clean uniform e Read and follow all manufacture service procedures before starting a repair on any hybrid vehicle Before servicing or testing the high voltage electrical system or di
26. resistances such as copper wire we use as conductors while those with high resistances such as rubber we use as insulators Several things determine a material s resistance e Number of free electrons in the outer shell of the atom e Length of the conductor a longer wire will have a higher resistance Page 11 of 88 MLR Electrical Study Guide 2013 Melior Inc e Cross Sectional Area The larger the circumference of a conductor is the less its resistance Example A 1 0 mm wire 16 Ga has less resistance than a 35 mm wire 22 Ga e Temperature generally as a material is heated its resistance increases exceptions to this rule will be seen later Other factors also affect the resistance in a circuit such as loose connections corrosion broken wire strands etc In contrast to the useful applications of resistance mentioned before these will cause a circuit to operate inadequately or not at all In later sections we will also become familiar with devices called resistors whose function it is to limit the current or voltage to another part of a circuit and Ohms thus control its operation l NAE p Resistance is measured in Ohms and is given the The standard unit of measure for resistance is known Greek letter Omega Q as the Ohm and is given the Greek symbol Omega Q An Ohm is defined as the amount of resistance that when applied to a one volt circuit will limit the current to one amp Thus on
27. send current through the battery in the opposite direction as during discharge This is the normal desired operation Generator Voltage Output A generator s output can be varied three ways e Alter the number of turns or windings in the stator stationary winding e Change the speed of rotor rotation e Vary the strength of the rotor s magnetic field The first two ways are determined from a design standpoint and the third is used by the voltage regulator to control the generator s voltage during operation If the number of windings in the stator is increased the magnetic field cuts through more conductors and amperage in the stator is increased If the speed of the rotor rotation is increased the magnetic lines of force are cut through with greater frequency increasing the voltage produced in the stator windings Rotor speed which increases with engine rpm is determined by pulley size and design Altering the rotor s magnetic field strength controls the generator s voltage output The stronger the field the greater the voltage induced in the stator Voltage regulators control generator output by varying the amount of current and thus the magnetic field which passes through the rotor rotating winding Generator Components A generator is made up of four primary components e Rotor and brushes e Stator e Diode bridge e Voltage regulator Page 79 of 88 MILR Electrical Study Guide 2013 Melior Inc Rotor a
28. tester s heavy clamps to the battery terminals and clamp the inductive amps probe around the negative battery cables e Start and run the engine at approximately 2000 rpm e Gradually rotate the load control knob until the ammeter indicates the specification for current Observe that the voltage remains in the acceptable range 13 to 15 volts Remove the load e Note Alternator current output should be within approximately 20 percent of its rated capacity e Press the DIODE key or rotate the tester s function selector knob to the diode stator test and observe the reading Page 87 of 88 MLR Electrical Study Guide 2013 Melior Inc Circuit Resistance Tests If you suspect poor test results are due to circuit problems rather Positive Side than the alternator regulator circuit resistance tests can pinpoint problems in the wiring These are voltage drop tests similar to the starting system tests described in the Starting Systems section To perform a circuit resistance test on the positive side of the circuit e Connect the positive probe to the alternator output terminal and the negative probe to the positive battery terminal as shown e Start and run the engine at approximately 2000 rpm e Adjust the load control knob to approximately half of the alternator s rated output e Observe the voltmeter reading Voltage drop should not exceed 5 volts in most cases Circuit resistance test for the ground side is similar to
29. the battery must be fully or below a specified value it fails the test and the battery near fully charged should be replaced To load test a battery testing equipment that can apply a load of the battery s CCA is needed This is usually in the 200 to 500 amp range The machine should be equipped with a voltmeter ammeter heavy gauge clamps and a load control knob The load is applied using a carbon pile and is adjusted with the load control knob Many different types of battery starting charging system testers are available and most are operated ina similar manner Refer to the manufacturer s instructions for use Load testing a battery is an effective way to test the battery s actual performance ability To perform a load test a specified current load is applied to the battery while its voltage is monitored If a battery s voltage drops below a specified value it fails the test and the battery should be replaced To load test a battery testing equipment that can apply a load of the battery s CCA is needed This is usually in the 200 to 500 amp range The machine should be equipped with a voltmeter ammeter heavy gauge clamps and a load control knob The load is applied using a carbon pile and is adjusted with the load control knob Many different types of battery starting charging system testers are available and most are operated in a similar manner Refer to the manufacturer s instructions for use Adapters Follow the equipmen
30. the generator Protection A fuse circuit breaker or fusible link is needed to prevent wiring damage from excessive circuit current Control A control device can either turn a load on and off or it can vary if a changing output is required Loads such as headlights or fan motors will be either on or off and will use switches or relays as controlling devices However applications such as instrument panel dimming fuel injection and transmission valves have variable outputs and are controlled by potentiometers transistors and Pulse Width Modulation computer signals Load A load is any part or component in a circuit that causes resistance to the current flow in the circuit All circuit loads will have a corresponding voltage drop Loads can be devices such as bulbs motors and actuators as well as unintentional items including bad connections and corrosion Ground All circuits must have a complete path to operate Automotive applications all terminate at ground or battery negative A ground return can be either hard wired to the battery negative or chassis grounded through the metal pieces of the vehicle Recall from Module 2 that case grounded components have an internal connection to their metal casing and become chassis grounded when installed in the vehicle Page 21 of 88 MLR Electrical Study Guide 2013 Melior Inc Series and Parallel Circuits There are 3 basic types of electrical circuits It is im
31. the test for Negative Side the positive side but the positive probe is connected to the negative battery terminal and the negative probe is connected to the alternator housing as shown If you use the starting and charging system tester s external volts leads the load clamps must be connected to the battery to power the meter s display Refer to the service manual for applicable specs and exact procedures Most applications specify not more than a 6 volt drop for both sides of the circuit Generator Repair Although some generator units are serviceable it is recommended that any repair of these units be left to electrical repair facilities with the proper tools and test equipment Page 88 of 88
32. to that point and would cause the unit to rotate as they pulled closer However just as the two points align the commutator switches the armature polarity and the new south point is now on the opposite side of the armature winding which causes it to attract the north point on the field coil and the rotation continues Page 7 of 88 MLR Electrical Study Guide 2013 Melior Inc To build a simple motor you need a loop of wire armature two permanent magnets used to form a north and south pole a commutator power source and set of brushes North Pole Shoe Field Coil DC motors can rotate clockwise or fae counter clockwise depending on current flow This allows one DC motor to control F the up and down motion of the power Power window motor windows or back and forth motion of power seats Gear used to Brushes move window Transformers Transformers are another type of device that works by electromagnetic induction A transformer is constructed Transformers with two separate windings a primary and a secondary ATIC LGERe ES GC ETCIECHONTS ER EEC wrapped around a common metal core When alternating SHE ei E current or pulsating DC current is applied to the primary applied voltage or current winding a voltage is created or induced into the secondary winding Transformers are classified as either Step up or Step down A Step up transformer will create a higher voltage in the secondary winding while
33. 5 volts that electrolyte charging at a high rate doesn t spew from the vent holes and that it does not feel excessively hot Battery Charging Charging a Single Battery Charging a single battery with a fast charger is a simple operation Ensure that there is sufficient electrolyte before charging the battery Remove the cell caps on non sealed batteries and add clean water to bring the electrolyte level to the bottom of the filler neck then replace the caps On sealed batteries check the built in hydrometer Do not attempt to charge a battery with a yellow clear eye replace the battery The eye should be dark If the eye is green proceed with a load test Page 63 of 88 MLR Electrical Study Guide 2013 Melior Inc e Ifthe battery is out of the vehicle install appropriate side Charging a Single Battery terminal adapters as described in the section on load testing If it is installed in the vehicle ensure that the cable ends and battery terminals are clean and in good condition and that the ignition is off e Considering the above factors make a judgment about how long and at what rate to charge the battery e Ensure that the charger is unplugged or turned off before connecting the charger clamps to the battery e Check the battery at least every hour for excessive heat or spewing of electrolyte and observe the AN SSN hydrometer High charging rates require checking more frequently After the battery
34. 50 CCA to 1000 CCA are common The higher the number the more powerful the battery and the longer it takes to recharge Cranking Amps CA The Cranking Amps rating is similar to the Cold Cranking Amps rating except the rated temperature is 32 F instead of 0 F Naturally this will yield a higher number than the CCA This rating may be useful in comparisons of cold weather operation between batteries Reserve Capacity RC The Reserve Capacity rating is the time in minutes required for a fully charged battery to reach a terminal voltage of 10 5 volts at 80 F when placed under a constant load of 25 amps This rating is useful in determining how long a vehicle with a fully charged battery can travel at night with zero generator output Typical ratings range from 90 to 200 minutes The battery in a vehicle with a charging system failure will become too weak to start the engine before the reserve capacity is reached It may however provide enough voltage to keep the spark plugs firing for a few minutes after this time Reserve Capacity ratings usually appear on a battery s label Ampere Hour Rating AH This rating has been largely replaced by the other ratings but is still sometimes used to calculate recharging times The Ampere Hour rating is a measurement of how much current a battery can produce for 20 hours at 80 F without the voltage dropping below 10 5 volts Chapter 2 Power Loss How Batteries Lose Power Several factors
35. Inc Headlights Quick Check Attempting to crank the engine with the headlights or dome light on while observing what happens may quickly point you in the right direction This chart lists possible conditions related causes and problem sources Result Possible Cause Problem Source stay bright connections connections connections proper operation 2 No cranking lights Battery discharged or malfunctioning Recharge and test battery dim significantly Very low temperature Check wiring circuit and battery Pinion jammed Poor alignment between cranking motor and flywheel free pinion check gear teeth Stuck armature Frozen bearings bent shaft loose Engine malfunction Check engine for loss of oil fermen Fee a 3 No cranking lights dim slightly Pinion not engaging Clean drive and armature shafts replace damaged parts Solenoid engages but no cranking Clean commutator replace Excessive resistance or open circuit in brushes repair poor connections cranking motor out brushes repair poor connections lights replace wiring Discharged or malfunctioning battery Recharge and test battery Voltage Drop Testing Voltage drop tests are useful for quickly finding sources of high resistance in the circuit Either the positive or the ground side can introduce excessive resistance to the circuit and both can be checked with a voltmeter Step 3 of the current draw test is actually a voltage drop test of the
36. MLR Electrical Stud Table of Contents MLR Electrical Study Guide cccccceseccccsseccceeseeeeeeseceeeeeeceeseneeeees UNIT 1 ELECTRICAL THEORY ccccccccceccceeeeeeeeaeeeesssseseeeeeeeeess Chapter 1 BISCtrO Mma sMetlSsccivcssectesonaiucrcvsssccivonadcderssanccevonenes Chapter 2 Magnetic COMPONENTS cecccecesseeeeeeseceeeeeeeeees saseeseeeeeneseeeseeenenenseseseeesesenees Chapter 3 Electrical Properties cccccsseccccesseceeeeseceeeeeeeeens UNIT 2 ELECTRICAL DEVICES AND CIRCUITS areoso a 14 Chapter 1 Circuit Components and SyMbOIS cccccssseesesseceesssseeeesee sco viiciecsssscosesdutioeseeets 14 Chapter 2 Ohm s Law and Circuits 0 c csesssressesereeres es zn roses 19 Chapter 3 Digital Multimeters csssersesssssrersersrsereses Et z _ lt zh aioe eee ee see see sase esses 24 Chapter 5 Testing Series and Parallel CirCuits ccccccccsseccceessececeesececeeecceeeuscceseuececeueceeseueeeess 32 Chapter 6 Diagnosing Using Wiring Diagrams ccccsscccccssecceeesscccceesececeeecceeeuscceseueceesueceesanseeess 36 Unit 3 AUTOMOTIVE BATTERIES cccceccccccssssssssesssssesseeeeee eee e OOOO 45 Chapter 1 Batteries Overview ccc cscserserssseresearsrsenes 01 tnz z mz mhnii rine Seseaee sess ssaeessesesseeeeee 45 Chapter 2 Power LOSS c scssssresscssrseessssercsserersasersenes ss _ _ a a
37. Sometimes it is necessary to reduce the amount of voltage drop across the branches of a parallel circuit to less than source voltage To accomplish this we use a circuit called Series Parallel A Series Parallel circuit works by inserting a resistor in series with a parallel network The series resistor will cause a voltage drop that leaves less voltage available to the branch loads and therefore reduces their currents From Head Park lamp switch FUSE BLOCK su iT w HEATER OD pe Heapup jy RT i T ve INSTRUMENT AS omy RADIO pm AND l Dim j DISPLAY lI pm CLUSTER _INPUT npurl AC InpuT CONTROL l DIM BRIGHT l inpuT 1 soup CONTROL l wopue l i i sae ASSEMBLY gt I s meee IH O a _ __ l L EUA HEATER AND AIC This illustration of a Dash Light circuit shows how changing the resistance of the rheostat dimmer control varies its voltage drop and in turn changes the voltage available to the dash bulbs which controls their brightness Question Question How would you calculate the total resistance of a How would you calculate the total current Series Parallel circuit Use the Ohm s Law formula I E R just as you would Calculate the parallel portion of the series parallel for any circuit In this case the voltage is the 12 volt circuit just as you would for and parallel network source and the resistance is the series parallel value and then add the ser
38. ading This is necessary because current drain may not occur after the battery is disconnected to install an ammeter Cycling the ignition key to the RUN and then to the OFF position may cause the drain to recur but there may be drains that will not recur unless the vehicle systems are reactivated in a road test The key must not be turned to the START position with an ammeter installed except with a high current shunt installed such as when checking starter draw The special tool does enable the vehicle to be driven to assure that all systems are ready for testing When using a hand held DVOM be sure to use the highest amperage range to prevent blowing the meter s fuse in a lower range range Furthermore be sure not to cause a current overload by opening a door courtesy lights or by any other means with the tool in the OFF position When testing is complete turn the special tool to the ON position continuity through battery cable to guard against current overload and never turn the tool to the OFF position with the vehicle s engine running To do so could damage the meter and the vehicle s electrical system Any time the battery is disconnected from the system you Memory Saver may want to use a memory saver This device plugs into the vehicle cigarette lighter receptacle and provides voltage to Usinea nanan serene halal fax the system when the battery is disconnected Using a retaining programmed information memory saver wil
39. adly it became fused to the cable and broke Note the internal corrosion on the strap and plates Page 55 of 88 MLR Electrical Study Guide 2013 Melior Inc When corrosion builds up between the points of contact it creates excessive resistance to current flow and can prevent starting and proper charging This type of bad connection may allow small amounts of current to pass but not the larger current needed for starting Note Avoid replacing corroded cable ends with units that splice to the end Universal Terminals of the cable These invite corrosion at the splice The splice also tends to are Not Recommended come loose and cause a poor connection Replace the cable if at all practical Battery Testing and Service There are several methods for determining the condition of a battery A battery that fails these tests can often be condemned immediately Electronic battery testers that run a series of tests on a battery are available These testers are simple to use and can determine the condition of batteries without having to take the time to recharge them However these testers may return a result of Charge and Retest This means the battery is insufficiently charged to be tested A battery must be fully charged in order to be accurately load tested Initial Assessment Battery testing begins with a visual inspection of the battery connections and cables A battery with a cracked case broken or loose posts or a
40. age 67 of 88 MLR Electrical Study Guide 2013 Melior Inc Pinion and Gear Reduction Several different types of drive mechanisms are used on starting motors but in all cases gear reduction occurs between the pinion and the flywheel The amount of gear reduction designed into the application is a balance between the torque required of the starter and the speed required for reliable engine starting PINION Proper disengagement of the pinion is critical to cranking motor operation Because of the gear reduction ratios if the pinion were to remain engaged after the engine started the flywheel would drive the armature at speeds that could damage the cranking motor This is where the overrunning clutch comes into play When the flywheel begins to drive the pinion the overrunning or one way clutch freewheels to prevent damage to the starter FLYWHEEL Starter Mounted Solenoid The starter mounted solenoid is a powerful Solenoid and Starter Motor electromagnetic coil that is energized with a relatively low amount of current when the ignition switch is turned to the START position When energized the solenoid draws a plunger into a coil and holds it there As the magnetic field created by the coil pulls the plunger in a shift lever moves the pinion toward the flywheel When the plunger reaches the end of its throw a contact disk is pushed into firm contact with two terminals One terminal is connected to the battery and
41. al for vehicles with manual transmissions Start the engine of the vehicle providing the jump Turn off the lights heater or other electrical loads Page 65 of 88 MLR Electrical Study Guide 2013 Melior Inc 3 Attach one end of one jumper cable to the positive terminal of the stalled vehicle battery and the other end of the same cable to the positive terminal of the donor good vehicle battery as shown 4 Attach one end of the remaining jumper cable to the negative terminal of the donor vehicle battery and the other end of that cable to a ground at least 12 inches from the battery of the stalled vehicle This procedure is used in order to reduce the chance of a battery explosion There is likely to be a spark when making the final connection due to the difference in voltage between the two systems If the spark occurs near a battery it could ignite explosive gasses Do not make the final connection to the negative battery terminal to metal tubing or anywhere gasoline fumes may be present Jumper Cable Hookup Battery Safety Keep your face away from batteries Wear safety glasses Make Certain Vehicles Do Not Touch 4 Or Frame Replacing a Battery Replacing a battery is typically a simple job There are some things to keep in mind however After installing a new battery the vehicle s starting and charging system should be checked to ensure satisfactory performance from the battery Battery terminals a
42. ary system voltage DUTY CYCLE TRANSITION Observe how the on off cycle can vary High Electrical Demands Keep in mind that the voltage regulator only limits the maximum voltage output of the generator When demands Teg BIG DAEN SEEE on the vehicle electrical system are such that the full output High electrical demands can cause the of the generator is insufficient the regulator will provide actual system voltage to be less than the continuous full field current in order to obtain the regulator setting maximum possible output from the generator In other words the regulator limits the maximum voltage the generator can produce however combining many high electrical loads on a vehicle can often cause the actual system voltage to be less than the regulator setting Methods of Regulating Voltage Several different methods of regulating system voltage have been used and late model vehicles are increasingly using electronic control modules to supplement or replace conventional voltage regulators Computerized ECM or PCM control of system voltage offers several benefits such as greater accuracy and consistency Other advantages include the ability to set diagnostic codes and to enhance driveability such as turning off the alternator at full throttle to reduce engine load Page 83 of 88 MLR Electrical Study Guide 2013 Melior Inc This diagram is an example of a PCM Control of System Voltage system in which vo
43. assist the technician in determining the fault with the system Orifice High Pressure Voltage Drop Low Pressure Voltage drop is the difference in electrical pressure between the two sides of a device Higher Vol tage Lower Voltage Voltage Drop UNIT 2 ELECTRICAL DEVICES AND CIRCUITS Chapter 1 Circuit Components and Symbols Batteries An automotive battery stores chemical energy that can be turned into electrical and mechanical energy This energy is used to operate automotive electrical systems The battery supplies power to the starter and ignition systems to start the engine The battery also supplies the extra power necessary for the electrical system when the vehicle s electrical load exceeds the supply from the charging system and acts as a voltage stabilizer in the electrical system Symbol In automotive circuits as with any electrical circuit current flows from the power source battery Therefore the battery is the first component in any electrical circuit Battery Page 14 of 88 MLR Electrical Study Guide 2013 Melior Inc Circuit Breakers A circuit breaker is a protection device designed to open when electrical current exceeds a calibrated amperage An electromechanical circuit breaker contains a metal strip made of two different metals bonded together called a bimetal strip When excesses current heat is applied the metal strip will separate opening the
44. ater than 2 volts indicates the terminal and cable end need cleaning Page 61 of 88 MLR Electrical Study Guide 2013 Melior Inc Using Battery Chargers A discharged battery that is otherwise good can be restored to a charged condition with the use of a battery charger The charger forces current through the battery and replaces the energy that has been drained The time required to bring the battery to full capacity depends on several factors e The condition of the battery Recharge Rate e State of charge of the battery e Battery temperature Recharging at a low rate is preferable e Battery size and rating e Rate of the charger rate selected A slow charge at a low rate of about 10 amps provides better results and less wear on the battery than a fast charge at high amperage This is especially true of batteries that have been in service for an extended period Generally the lowest rate that time permits should be used Battery Condition A battery that is sulfated will not accept a high current Attempting to fast charge a sulfated battery will cause it to overheat No battery should be allowed to reach a temperature of over 120 F or a voltage of over 15 5 volts when charging When charging a partially sulfated battery a lower charging rate may allow the sulfate to break down permitting the battery to be recharged and returned to service Similarly a battery that is severely discharged will not accept a
45. but because it will give false readings Resistance measurements are made according to these steps and shown in the figure 1 Power must be off 2 Insert the meter leads in the COM and VO inputs 3 Turn the rotary dial to the Q position Place the leads across the component 5 Do not allow your fingers to touch the ends of the leads since it will change the reading Page 26 of 88 MLR Electrical Study Guide 2013 Melior Inc Converting Values When working with meters it may be necessary to convert the meter reading to a higher or lower unit of measurement When converting units remember the following rules e When converting from a larger unit to smaller unit multiply o Example 1 volt is converted to millivolts by multiplying 1 x 1000 1000mV e When converting from smaller units to the larger divide o Example 500 mV is converted to volts by dividing 500 1000 5V Below is a diagram that may come in handy when doing NL AND FROM BASE UNITS conversions Using the table below the base unit lt lt lt lt r M K m represents the number you are starting with By moving MEGA KILO MILLI MICRO the decimal right or left you can easily convert from your ae base unit to the appropriate measurement Automotive Wire Applications Wires in automotive applications typically come Automotive Wire Applications in one of three different configurations braided a n twi
46. c with PTCs POWER WINDOW i CONTROL z MOOLLE P aul fe tone S OWN CURRENT T ky 7 25 INPUT POWER SENSE FRONT WINDOW BITCH INPUT uP STOP INPUT CONTROL RH FRONT POWER WINDOW MOTOR LH FRONT POWER WIN DOr MOTOR A PTC is a thermistor that works by greatly increasing its resistance when too much current generates excessive heat in the device As the resistance increases the current in the circuit is reduced which protects the wiring from damage Fusible Links Like fuses fusible links are single use devices that melt internally from heat caused by too much current Although they look like typical wires fusible links have an insulation designed to withstand Fusible Links Fusible links should be 4 sizes a greater amount of heat than regular wire insulation This smaller than the wire they protect prevents inadvertent shorting to ground during a failure caused by excessive current Fusible links are being used less in modern applications as fuses with higher amperage ratings have become available Page 37 of 88 MLR Electrical Study Guide 2013 Melior Inc When replacing an open fusible link never exceed nine inches in length and use a link that is four sizes smaller than the circuit wire For example a 14 gauge wire would be protected with an 18 gauge fusible link This will ensure that the link burns before the circuit wire An open fuse link can also be ver
47. cessive gassing also carries away water from the electrolyte In a sealed battery the water cannot be replaced and the battery will fail prematurely In a conventional battery the water can be replaced but if the level is far enough below the tops of the plates to allow them to become dry they harden and become chemically inactive Overcharging promotes corrosion on the plates and may cause the battery to heat up Severe overcharging can cause a battery to swell puffing the ends out noticeably A strong acidic or sulfurous smell may also be noticed Use care when working around a battery that has been overcharged as an overflow or residue of concentrated electrolyte is likely to be present The battery tray and hold down should be cleaned and treated to prevent deterioration A mixture of baking soda and water or a commercially available treatment are effective for this purpose Undercharging and the Result A Sulfated Battery A battery that is less than fully charged is obviously not storing its capacity of energy More importantly it will be permanently damaged if left in this condition very long Normal Sulfation Sulfation In Progress Permanent Sulfation Page 52 of 88 MLR Electrical Study Guide 2013 Melior Inc A battery that remains in a discharged condition for longer than approximately 30 days will begin to sulfate Sulfating occurs when the lead sulfate on the plates crystallizes becoming dense an
48. circuits and grounded circuits Open Circuits An open circuit does not always indicate a fault For example a horn circuit is normally open until the horn button is depressed An open circuit that results in circuit failure is an unintentional opening in the circuit such as severed wiring or a faulty switch Page 39 of 88 MLR Electrical Study Guide 2013 Melior Inc Normal Operation Open Circuit 12 Volts 12 Volts MA OTA 1 PA k i ce pa urrent cannot low to Horn Fuse the horn Therefore the horn will not blow In this horn circuit the horn switch relay is hom switch and is OPEN Therefore there is no current flowing and Horn Fuse the horn will not blow Closed Horn Relay Horn Relay Horn Horn Horn Switch Ho Horn Switch l l Short Circuit 12 Volts YTA FIS cannot slow to the horn In this case the fuse should blow to protect Horn Fuse the circuit wiring Horn Relay Horn Horn Switch l Short Circuit A short circuit will allow current to flow out of a circuit by providing a path out of the circuit that has less resistance than the circuit itself As a result shorted circuits have low resistance as we learned when we covered Ohm s law this results in high current flow Fuses and circuit breakers were designed specifically to protect against the severe consequences this high current flow can have and the normal result of a short c
49. cle body The pigtail connects the body ground to the engine ground and it must be connected for the starting and charging system to work properly Acid fumes and water vapor are formed and released during the chemical reactions of charging This gassing causes the loss of electrolyte Conventional batteries have removable vent caps permitting the electrolyte levels to be checked and topped off as well as to allow chemical testing Maintenance free batteries are designed to minimize gassing Each battery cell is a separate unit that produces 2 1 volts A 12 volt automotive battery contains six cells connected in series for a total of 12 6 volts Page 46 of 88 MLR Electrical Study Guide 2013 Melior Inc Dual Batteries in Parallel Many diesel applications use two 12 volt batteries connected in parallel to 7 provide the high current required to O EEA a crank a diesel engine Batteries connected in this fashion still supply 12 volts but have twice the current capacity of a single battery Chassies Ground Connector Starter Motor Secondary Negative Battery Cable Secondary Positive Battery Cable Negative Battery Cable Positive Battery Cable Other Types of Batteries Low Maintenance and Maintenance Free Batteries Removable Caps Many batteries are marketed as maintenance free meaning ON On some batteries it may not be water should not need to be added during the life of the
50. d To prevent this loading look for a meter with high Input Impedance generally the higher the better This becomes even more critical when measuring electronic components as some low impedance meters can actually cause damage to those circuits Our Fluke 87 has an input impedance of 10 000 000 Ohms 10MQ Page 24 of 88 MILR Electrical Study Guide 2013 Melior Inc Digital Display The Fluke 87 Display is a digital and analog LCD readout screen for all meter functions Turning the meter on while holding any button will allow the user to see all of the Display possible display segments on the screen Each screen function me Pushbuttons is self tested when the meter is turned on and so to save battery power the meter will turn itself off if not used for a certain amount of time Rotary Dial Pushbuttons Eight pushbuttons are used on the Fluke 87 to change display readouts and some rotary dial functions Tena Rotary Dial The rotary dial has eight positions for selecting the desired measurement Fluke 87 Main Navigation Input Terminals There are four input terminals at the bottom of the meter for inserting test probes The Fluke 87 is also equipped with a feature called Input Alert This feature will emit a constant chirp if a lead is inserted into either the A or the mA UA terminal input and the rotary dial is not turned to the mA wA or uA position This prevents damage to fu
51. d by experiment the relationship between voltage amperage and resistance The mathematical equation used to determine the relationship between voltage amperage and resistance is called Ohm s law In electrical circuitry if any one of the three variables V A Q changes it will affect at least one of the other two In Ohm s Law equations e E Electromotive Force Voltage i Intensity Amperage e R Resistance Ohms A value for any one of these variables can be found as long as the other two are known Page 19 of 88 MLR Electrical Study Guide 2013 Melior Inc Formulas and Relationships Formulas The primary formula for Ohm s Law is Ohm s Law Formulas E IxR e VoltageE IxR e Currentl E R or e Resistance R E Volts Amps x Ohms This tells us that if we multiply the current in amps times the resistance in ohms we can find the applied voltage or voltage drop To find an unknown current we use I E R or A V Q Divide the voltage by the resistance to find the current Resistance is found with R E I or Q V A Divide the voltage by the current to find resistance Relationships To better understand the relationships between voltage amperage and resistance consider the following rules Directly Proportional means that as one variable increases another variable will increase in proportion e If voltage increases and resistance remains the same current will increase e
52. d hard and difficult to break down If the process has not gone too far the battery may be restored to a serviceable condition by recharging at a reduced rate A long slow charge at half the normal rate may succeed in recharging the battery A battery in this condition will not accept a normal charging rate and will simply overheat In the same manner a battery that remains in service in a partially charged condition due to poor connections abnormally high electrical demands or a low charging rate will become partially sulfated and battery performance will be diminished The result will be premature failure Parasitic Loads In modern vehicles batteries are constantly being discharged by very small current loads needed to power the High Parasitic Draw memory circuits of electrical devices such as electronic Some special applications may have a control modules and digital clocks These are known as high parasitic draw up to 06 amps parasitic loads because the circuits involved are always connected to the battery and continue to drain small amounts of current even when the ignition is turned off One or more control modules may at some time exhibit a failure mode that causes a high parasitic drain The total parasitic draw for a particular vehicle varies according to the level of electrical equipment on the automobile For example a fully equipped luxury car would normally have a much greater parasitic draw than a smaller economy
53. d know the locations of fire extinguishers and the first aid kit First aid kits should contain a bottle of sterile acid neutralizing eyewash Larger facilities often have an emergency shower and eyewash station located in the battery storage and service area Batteries release explosive hydrogen and oxygen gasses A battery can explode with a sound like a shotgun discharging rupturing the case and spraying acid in all directions Avoid creating sparks around a battery The following guidelines will help to reduce the chance of arcing or sparks e The ground terminal of a battery should always be disconnected first and reconnected last e Connect battery chargers to a battery before plugging in the charger e When jump starting a vehicle follow the proper procedure Do not connect the jumper cable to the negative battery terminal of the vehicle you are jump starting The procedure to follow will be presented later in this section e Do not attempt to charge jump start or load test a battery with a broken or loose post a cracked case or one in which the electrolyte is frozen Accidental shorting of the positive battery terminal or any system voltage source to ground with a tool or metal object can cause severe burns Metal jewelry can be heated to its melting point in seconds Even a brief short of this nature can damage the PCM and other electronic components gt Never hammer on a battery terminal or cable end or attempt to r
54. e which part is malfunctioning Part of system testing requires the use of a Digital Multimeter sometimes also called a Digital Volt Ohm Meter DVOM A DMM is a versatile tool that allows for the measurement of Voltage Current Resistance Capacitance Frequency Pulse Width and other aspects of electricity Choosing a Good Digital Multimeter A good digital multi meter must have a high input impedance Fluke 87 The Fluke 87 is a multi meter that operates on a base 4 principle Measurement ranges will be 4 40 400 4000 etc For instance on a voltage setting the maximum value that can be measured will be 4V 40V 400V or 4000V depending on the scale selected Some other brands of meters are base 2 2 20 200 2000 etc or base 10 1 10 100 1000 etc Either type will work equally well as long as the technician learns to read the meter properly and accurately As with all things meters come with different levels of features quality and prices A technician considering the purchase of a meter should keep two things in mind e Does it have all the functions need e What is its input impedance Impedance is the input resistance a meter has It prevents the meter from becoming a component of the circuit and affecting the circuit operation Some lower quality meters have a tendency to load the circuit being tested and thus affect not only the operation of the devices itself but also cause incorrect readings to be displaye
55. e higher operating temperature will shorten the life of the lamp 2 Take great care when servicing or changing headlamps Handle all lamps new or old with great care Headlamps are under pressure breaking them can cause an explosion sending sharp pieces of glass flying 3 Install new lamps immediately after removing from packaging Allowing them to lay on a workbench to long will allow them to attract dust and moisture 4 Always replace a lamp with one correct part number Never install a lamp that is not the correct wattage and voltage rating 5 Always ensure the headlamp socket is installed and sealed properly after replacing a headlamp Not doing so will allow the lens to become cloudy or the headlamp assemble cover may fill with water shorting the life of the lamp Headlight circuits on most vehicles are protected by a circuit breaker This is a safety precaution that will allow headlight to operate momentarily ON and OFF in case there is a short circuit in the headlight circuit If this condition should occur do not operated the vehicle until repaired HID Headlights CAUTION On HID High Intensity Discharge headlamps never test using a DMM or test light On HID headlamps a voltage of approximately 30000 is momentarily applied to the bulbs Never touch the high voltage sockets on any vehicle equipped with HID headlights or a serious personal injury could occur On HID headlamps the test and inspection procedure can be performed as fo
56. e volt through one ohm equals one amp Students may choose to use either the Ohm symbol or a capital R to signify resistance We will return to resistance and ohms later Power When studying power there are a few terms that you should be familiar with Power Power is the rate of doing work Electrical power gt is a rate of Power is rated in watts and is a work done at 1 joule per second Mechanical power is work measurement of work output The formula f a done at a rate of 550 foot pounds per second ormula tor measuring power Is P IxE Joule A unit of energy One joule is the amount of energy i required to move one coulomb of charge between 2 points with There are alternative formulas for a potential difference of 1 volt Also 3x106 joule equals 1kw calculating power Coulomb The basic unit of charge The amount of electricity e P IxR represented by 6 25x1018 electrons e P E R For purpose of this course we will focus on electrical power Unlike Voltage Current and Resistance Power is not a direct measurement for an electrical property Power is the output or rate of work performed by a machine or electrical electronic circuit Gasoline diesel engines and electric motors are rated as to the number of horsepower they produce However many other electrical devices e g light bulbs are rated by the amount of power they consume rather than by output Generally those things that are rated in watts consumed have a different fo
57. ed a slow chemical reaction causes the battery to self discharge A significant Stored Batteries amount of power is lost after one month and after four aera dinate E A E A E months of storage at 80 F a battery can be 50 discharged For this reason stored batteries must be recharged periodically before they become significantly discharged Self Discharge Rates Cold temperatures on the other hand slow the Self Discharge Rates rate of self discharge A battery can be stored at i AON ig A A CEE 0 F for an extended period without self TR b SS T raa a a S a R S S a discharging N LLL Ll ss ag TNE Skt CO Ra SB Dirt and or electrolyte residue between the See aEz battery terminals can speed self discharging Current can track across the residue to ground so the area between the terminals should be clean 2 This is more prevalent with top post batteries Contrary to popular myth setting a battery ona cement or concrete floor has no effect on the rate of self discharge coun nmnnannaene se DAYS STANDING Corrosion Corrosion forms on and around the battery cable ends between the cable ends on the battery terminals and inside the battery The positive terminal is particularly susceptible to corrosion build up which can creep down the cable where it is not visible Look for a swollen cable or discolored insulation The positive terminal of the battery to the right corroded so b
58. emove a cable by prying To avoid damage to the battery or terminals and possible personal injury use a clamp spreading tool if the clamp doesn t seat at the bottom of the post and use a cable clamp puller to remove stubborn clamps Avoid contact with the white flaky or powdery corrosion that builds up around battery terminals and trays This substance is sulfate and or sulfide it is corrosive and can cause chemical burns Page 49 of 88 MILR Electrical Study Guide 2013 Melior Inc Always follow all general safetey guidelines for servicing motor vehicles with regards to adequate venilation working around hot or moving parts proper use of parking brake gear selector wheel blocks and disabling fuel or ignition systems Refer to equipment User s Manual and vehicle Service Manual Temperature Efficiency and Ratings Battery Temperature and Efficiency As temperatures fall chemical reactions in the battery are slowed and available power is reduced At the same time the current required by the starter to crank the engine increases due to thickening of the motor oil Cold and Batteries Cold temperatures reduce a battery s available power e At 80 F 100 percent of the battery s starting power is available e At 32 F 65 percent of the battery s power is available but current draw may be increased to 200 percent of normal e At0 F 45 percent of the battery s power is available but the sta
59. engaging the pinion gear with the flywheel and the contact disc connects the solenoid s battery and starter terminals High current then flows from the battery cable through the solenoid to the starter motor The starter motor case completes the circuit to ground and starting begins CHARGING oY aT EM IGNITION SWITCH LOCE FUSIBLE LINK i T n 4 BATTERY JUNCTION BLOCK I7 7 TZT j CRANE l nee ie FUSE BLOCK Io A FUSIBLE LINK 7 E i ia a Lib _ D __ co PARKINEUTRAL POSITION PNP amp BACKUP LAMPS SWITCH J 2 STARTER RELAY FUSIBLE LINK p E A STARTER SOLENOID FLUMIGER FLYWHEEL SHIFT LEVER STARTER MOTOR IW DRIVE ASSEMBLY Page 70 of 88 MLR Electrical Study Guide 2013 Melior Inc Current Draw and Torque A direct relationship exists between the current draw of the starter CMEF motor and the torque it produces Torque and current flow are both greatest when the armature is stalled Electric motor stall occurs at that point when voltage has first been applied but the motor has not yet begun to turn HIGH TORQUE AND CURRENT LOW SPEED HIGH AND CEMF Chapter 2 Starting System Diagnosis and Service Starting System Diagnosis Diagnosis of starting system failures is straightforward Common causes of starting system problems are e Dead battery e Poor battery cable connections e Burned solenoid contacts e B
60. er its diameter must be to ensure that the additional resistance does not affect its current carrying capability Refer to the chart which shows a comparison of the wire length to wire size requirement for a given amperage These figures are typical for 12 volt systems Wire length 0 5 20 20 20 20 20 18 18 Page 28 of 88 MLR Electrical Study Guide 2013 Melior Inc Stripping Every technician knows that in order to join two wires together or Typical Wire Strippers to install a new terminal on a wire some insulation must first be sraippeo wine OTER CASTING removed from the wire It sounds simple enough unfortunately SE ENA too often bad stripping technique causes the connection to be less than ideal and possibly inoperative GRIPPER JAWS The first thing to remember is to remove only as much insulation as necessary to do the job Too little bare wire may cause a bad connection and too much may expose the circuit to inadvertent contact with another circuit or to ground Secondly always use a proper stripping tool in good condition Do not use a knife a pair of side cutters or any other type of sharp instrument as these will nick or cut some of the strands called ringing the wire and reduce the amount of amperage the circuit can carry Using a good pair of wire strippers also reduces the chance of stretching and weakening the strands Splicing Using Splice Sleeves Whenever two wires need to be joined
61. erred to as a full wave rectifier commonly consists of six diodes which convert all of the AC voltage to DC This illustration shows a four diode bridge and its output waveform pattern Delta Stator This diagram shows a delta stator wired to a six diode bridge Note that the current is blocked from flowing from the stator to the grounded side of the bridge Page 81 of 88 MILR Electrical Study Guide 2013 Melior Inc Here a typical diode bridge is illustrated Voltage Regulator All alternators have a voltage regulator and most are internally mounted as part of the unit This illustration shows some typical alternators with internal regulators and with both internal and external cooling fans Limiting Voltage Voltage regulators limit generator output to a level approximately two volts higher than battery voltage This higher voltage level provides the push necessary to force current through the battery recharging it when the engine is running at a sufficient soeed and without excessive electrical loads As shown in this illustration system voltage must be kept to a safe level 14 7 V 5 to prevent damage to electrical components Temperature vs Voltage Voltage regulators sense system voltage and many also sense battery or generator temperature Regulators will increase the system voltage setting to compensate for cooler temperatures and reduce voltage output for higher temperatures In this
62. es not perform the real work in an electrical circuit Page 9 of 88 MLR Electrical Study Guide 2013 Melior Inc Source Voltage Source voltage is a term used to refer to the amount of voltage available to move electrons through a circuit Source Voltage For most automotive applications source voltage Source voltage is the voltage applied to a should be in the 12 14 volt range However many of FEN ETRER ECHO OTCTICRe RG GOT today s sensors operate on a 5V supply while some actuators will use 7 8 or 10 volts and electronic computer components may use less than one volt It is most important for the electrical technician to be aware of the amount of voltage that should be applied to a circuit to insure that misdiagnosis does not occur Current Current is the movement of electrons in a circuit Current Like our voltage and water pressure analogy from before current would be compared to the actual Current is the movement of electrons through a water moving through the hose It is current conductor rather than voltage or power which causes the Conventional current flow views current as lights to shine the motors to turn and the fuses D l ibl flowing from positive to negative Electron current O DIOW flow views current as flowing from negative to Unlike voltage which is the presence of electrons positive current is the movement of electrons through some sort of conductor The greater the number of
63. etimes called push i j Z Uf TERMINAL to seat are inserted from the back of the connector while those p E PUSH SMALL PICK BETWEEN TERMINAL AND CONNECTOR BODY terminals with the tang facing forward pull to seat are inserted lt INSERTION from the front of the connector Attempting to remove a terminal in the wrong direction will obviously cause damage to Wij _ inna the terminal and possibly the connector Pull to seat terminals PICK RELEASING LOCKING LOCKING TANG TANG must also have their wires pushed completely through the connector before a terminal is attached In short a great deal of frustration can be avoided by verifying the type of terminal being used before attempting to remove it Terminal Crimping Let s cover some good crimping techniques e Strip an amount of insulation such that the bare wire shows on both sides of the core crimp but does not extend into the insulation crimp area The core should also not be long enough to interfere with the mating end of the terminal see illustration If it is a pull to seat terminal the wire must be inserted through the connector first Do not twist the wire ends as that will result in less wire to terminal contact e Select the proper anvil on the crimping tool and crimp the core first using firm but not excessive force Too much force will bend the terminal Pliers are never to be used for terminal crimping It is also necessary to crimp the c
64. f 88 MLR Electrical Study Guide 2013 Melior Inc Measurements Voltage Measurement To properly configure a meter for voltage measurements follow these steps and refer to figure shown here 1 Insert the meter leads into the COM and VO inputs 2 Turn the rotary dial to the AC or DC Volt position 3 Place the leads across the component to be tested voltage drop 4 Apply power to the circuit Current Measurement Caution e To prevent blown fuses check your meter installation thoroughly before applying power Remember in this mode all of the current in the circuit will pass through the meter e Never place leads across a component when measuring amperage To measure current follow this procedure and refer to figure shown 1 Insert the meter leads into the A and COM inputs 2 Turn the rotary dial to the mA A position Make an open in the circuit 4 Place the meter leads to complete the circuit leads must be inserted so that all current flows through meter 5 Apply power to the circuit When measuring circuit current always begin with the red lead in the A 10 amp input terminal The Lad W iehor PhO lead may be moved to the mA input only after you have determined that the current is below the maximum 1A rating for that terminal Resistance measurement Note When measuring resistance it is important to make sure the power is off This is done not because it will damage the meter
65. he testing method used be sure the battery is bad and not merely discharged before recommending a replacement Hydrometer Testing Hydrometers are used to measure the specific gravity of electrolyte A hydrometer with a single float and a numerically graduated scale is recommended This type of hydrometer usually has a built in thermometer to make necessary temperature corrections Smaller hydrometers that use multiple colored balls are generally not reliable The hydrometer pictured is a Snap on BB4A This chart shows the charge level and voltage for specific gravity readings taken with a hydrometer Charge Level Specific Gravity and Voltage Charge Level Specific Gravity Voltage 12 Voltage 6 100 1 270 12 60 6 3 75 1 225 12 45 62 50 1 190 12 24 6 1 25 1 155 12 06 6 0 Discharged 1 120 11 89 6 0 Built In Hydrometers Many maintenance free batteries are equipped with a built in hydrometer Hydrometers will indicate the state of SUSU a eID SLATE SCAR charge in only one cell of the battery and therefore have Keep in mind that a built in limited diagnostic value The built in hydrometer contains hydrometer indicates the state of a ball usually green and a round sight window or eye on charge for only one cell top of the battery Information on interpreting built in hydrometer readings is printed on the top of most batteries Wipe the window clean and look straight down at it in sufficient light The eye will ap
66. he time to become familiar with these symbols When working with an electrical system it s sometimes necessary to perform voltage drop or continuity tests Modern wiring diagrams use numbers and letters to help identify circuit connector locations How many electrical symbols can you name in the diagram below Most electrical diagrams may contain additional information such as component location and wire size Most modern wiring diagrams are drawn from the top of the page to bottom Often any component that is not drawn showing all electrical wires will have a page reference number beside it Chapter 2 Ohm s Law and Circuits Ohm s Law i en Male connector m _ Female connector _ Rubber Grommet 3mm cross section wire size and is light green in color 3 LT GRN 170 Circuit number C301 Connector number 5202 Pin number of wire inside connector a as ae The letter S indicates a splice where two G304 G305 or more wires are joined together The 202 indicates the second splice in the 200 area typically the engine compartment The letter G indicates a ground connection The broken lines on connection G 304 indicate that not all wires at this connection are shown Headlight Switch the broken vA Dimmer Switch fines around the headlight switch indicate that not all wires to switch are shown ig this diagram In the early 19th century George Simon Ohm prove
67. high current A completely discharged battery will take more than twice as long to charge as a half charged battery of the same size As the state of charge increases the battery accepts more current and the remaining time required for recharging is reduced A completely discharged battery may not have sufficient voltage to activate the polarity protection circuits on some chargers These circuits are designed to prevent accidental reversing of the charger leads at the battery and usually require at least two volts from the battery before they allow the charger to operate Carefully follow the manufacturer s instructions on bypassing or overriding this circuitry when charging a completely drained battery Using a high charging rate to fast charge a battery will not damage a battery that is in good condition however it will not bring the battery to as full a state of charge as a slower rate will To recharge a severely discharged battery in a reasonably short period of time start with a high charging rate of around 20 to 35 amps As time permits switch to a lower charging rate of around 5 to 10 amps to finish Higher beginning charge rates may be used but they do not promote extended battery life Some chargers automatically reduce the charging rate as the battery s state of charge increases Page 62 of 88 MLR Electrical Study Guide 2013 Melior Inc Battery Temperature We have said that cold temperatures slow the chemical reaction
68. ical Study Guide 2013 Melior Inc Terminals From time to time it will be necessary to replace terminal pins for loose connections corrosion or breakage It is important that technicians follow a correct procedure in replacing terminals to reduce the possibility of a repeat failure Some of the problems to be avoided include stripping too much insulation stripping too little insulation excessive crimping force that bends and weakens the terminal and too little crimping force that causes a bad connection Releasing Terminals There are many types of connector terminals used throughout the automotive industry and there are numerous methods for the removal and replacement of those terminals Most terminals will have a tang or finger that holds the terminal once it is clicked into place Others use some form of cap or wedge that is inserted to hold several terminals all at once Some use a rubber insulator that seals numerous wires while others have individual insulators for each wire Most of the terminals however will have a tang and can be Using a Pick removed by inserting a small pick between the connector and for Terminal Removal terminal and compressing the tang see illustration Technicians need to be aware that there are two types of these terminals one with the tang facing rearward toward the wires and one with the tang facing forward It s important to note that those terminals with the tang facing rearward som
69. ies resistance to that total determined in the last step Page 35 of 88 MLR Electrical Study Guide 2013 Melior Inc Chapter 6 Diagnosing Using Wiring Diagrams With an understanding of Voltage Current and Resistance we can now turn our attention back to the devices that determine those values Circuit Protectors As introduced in Module 2 three types of circuit protectors are used in modern automotive applications fuses circuit Circuit Protectors breakers and fusible links The primary function of these Circuit protectors are used to prevent devices is to protect the wiring from damage should a circuit ofiline demiaee tron CNE failure cause excessive current Although circuit protectors are rated in amps it is actually the heat caused by too much current that causes the device to open the circuit Fuses Fuses are the most common circuit protectors in automotive use and are rated from 5 A to 80 A They are one use devices with a metal strip inside that melts from the heat caused by exceeding the current rating of the strip The most common fuse types are the ATC ATO Auto Fuse or blade style Mini Fuse and Maxi Fuse As shown in the graph here different colors are used to identify the amperage values of the various fuses Assorted Automotive Fuses Fuse Colors Current Rating in Amperes Fuse Color Auto Fuse Mini Fuse ey D Side l 5 Tan PAL Fuse Maxituse j a Mini Fuse a daa
70. ified by pulling its ends to see if it stretches which shows failure a Switches Switches are simply on off devices used to open or close an electrical circuit You are already familiar with some types of switches from the first two modules of this course There are various types of switches that are categorized by the number of positions they have as well as the number of circuits they control Some of the most common types are given below Single Pole Single Throw SPST Controls one circuit with two positions ON OFF Single Pole Double Throw SPDT One circuit with three positions two ON positions with a center OFF position Double Pole Single Throw DPST Two circuits with two positions Double Pole Double Throw DPDT Two circuits with three positions Switches are rated by the amount of current the Switch Type Examples contacts can carry Resistors Resistors are devices made of carbon or ceramic which are used to limit the voltage or current in a circuit They can be either fixed or variable and will be rated both in terms of value ohms and power watts STH BAND TOLERANCE IN 3RD BAND OF ZEROES 2ND BANO 2ND DIGIT IST BAND 1ST DIGIT The value of a fixed resistor can be read from its color bands Each resistor has several color bands that should be offset to one end Hold the resistor so that the color bands are on your left note the colors and compare them to the chart if
71. imit on the amount of voltage generated and sent to the battery and accessories thus protecting them from damage Page 77 of 88 MLR Electrical Study Guide 2013 Melior Inc e Battery receives electric power from the generator Supplies initial current to energize the generator Provides for electrical needs when generator output is insufficient Helps stabilize generator output e Drive belt transmits mechanical power from the engine to the generator pulley e Charge indicator voltmeter or ammeter and or generator warning lamp Generators and Their Functions Generators are the primary components of charging systems Just as motors convert electrical energy into Generator Operation motion using conductors and electromagnetic fields Generators use the principle of generators use the same principles to convert electromagnetic induction to perform their mechanical rotary energy into electrical energy In functions Induction occurs when a conductor other words instead of using electrical power to turn moves through a magnetic field a starter mechanical power is used to turn the generator which produces electricity Motors and generators both use the principle of electromagnetic induction to perform their respective functions The increased output possible with newer AC generator compared to older DC generators is due to a fundamental difference in design In a DC generator the conductor windings armature r
72. ircuit is a blown fuse or a tripped breaker However short circuits can still result in major circuit meltdowns and fires Grounded 12 Volts Circuit a rites a the E dh is before the horn switch The results would be a horn that blows Horn Fuse continually Horn Relay Horn Horn Switch Le Page 40 of 88 MLR Electrical Study Guide 2013 Melior Inc Grounded Circuit In an unintentionally grounded circuit there is an unintended current path to ground after the load A component that is grounded in this way will operate continually until either the ground or the source of power are removed When diagnosing opens shorts and grounds always use a wiring diagram to determine voltage drops throughout the circuit Headlight Circuits Headlight system operation and service precautions On several modern vehicle headlights are used for both day and night driving During the day headlights operate as daytime running lights Some manufactures use the same lamps for both day and night driving While others use separate lamps for day and night operation Systems that use the same headlamps for day operation will normally wire the front lamps in series dropping 6 volts at each headlamp There are several precautions that should be used when servicing headlamps 1 Avoid touching the glass of any headlamp A thin film of oil from your hands and fingers will cause the lamp to operate at a higher temperature Th
73. is charged check the electrolyte level and perform a load test Three Minute Charge Test The three minute charge test or quick charge test can be used to determine if a battery will accept a charge A battery that fails this test usually has sulfated plates To perform a three minute charge test connect a battery charger as previously outlined Connect and observe a voltmeter while charging the battery at a rate of 30 to 40 amps If the voltage rises above 15 5 volts replace the battery Charging Multiple Batteries Larger service centers may have a battery charger for charging multiple batteries at once These chargers are usually maintained at a low charging rate of three to 10 amps per battery and are used for slow trickle charging The charger and batteries are collectively referred to as the charging line or charging rack The charging line should be carefully monitored throughout the day Two different types of chargers can be used for group charging batteries These are e Current Limiting constant current or series chargers e Voltage Limiting constant voltage or parallel chargers With series chargers the batteries are connected in series so that each battery receives the same amount of current As such the charging procedures are different from parallel chargers With parallel chargers the batteries are connected in parallel so that the charging current is divided among the batteries Each battery receives on
74. is completed to ground The circuit current causes the solenoid contact points to close completing the cranking motor s circuit to ground and the battery is connected to the starter The starting system circuit will be covered in more detail but first let s examine some starter engagement components Note that in the system pictured here used on many Fords the solenoid does not engage the pinion with the flywheel it is merely a high current relay This is not a true solenoid because it does not produce linear movement but it is often referred to as a solenoid Engine Crankshaft Pinion Gear Motor Drive Mechanism The motor drive mechanism is the component through which power is transmitted from the starter armature to the engine flywheel during cranking The main components of the drive mechanism are the pinion gear and the overrunning clutch These components work together with one of the several methods used on various vehicles to engage the pinion with the flywheel As the armature spins it turns the pinion gear As Typical Motor Drive Mechanism the vehicle s key is held in the START position the Assist spring pinion gear meshes with teeth on the flywheel as 7 voltage is applied to the starter motor When the key is released from the START position a return j f spring disengages the pinion from the flywheel L ia a ae ring Thrust collar Overrunning clutch kas Pinion P
75. it First aid kits should contain a bottle of sterile acid neutralizing eyewash Larger facilities often have an emergency shower and eyewash station located in the battery storage and service area What is Electricity In order to properly diagnose and repair automotive electrical systems a technician must first have an understanding of how those systems operate In this section we will look at electrical fundamentals and how they determine the construction and application of all automotive circuits For the purposes of an automotive technician electricity is best defined as The movement of electrons through a conductor having the ability to do work In order to understand how these electrons move one must understand how matter and energy interact at an atomic level Atoms We have all studied the atom and how it is composed of a nucleus including Protons which have a positive charge and Neutrons which have no charge with Electrons revolving around it which have a negative charge We also know that each type of atom has a different number of electrons around its fo lt a e Protons f Neutrons O P Electrons amp N e f A F ff f I e N A Fa l Fd ri if perimeter X Hydrogen Carbon amp Atoms are made up of protons and neutrons in the nucleus and electrons in orbit around the nucleus Page 3 of 88 MLR Electrical Study Guide 2013 Melior Inc Atomic S
76. it is advisable to crimp the wires Splice Crimp Tool into a splice sleeve Splice sleeves are connectors that have both a metal insert to make the electrical connection and a special glue that when heated will hold the wires together by the insulation The glue will also protect the connection against exposure to weather that could corrode or break the wires Splice sleeves come in three sizes small medium and large and in the colors red blue and yellow respectively Refer to this figure for an illustration of the proper procedure for splice sleeve installation Splice Sleeve Installation e Strip each wire just enough that the bare wire is Splice Sleeve Crimping Steps exposed outside of the metal insert The notch in INSERT WIRE ee APPLY HEAT the middle of the connector will prevent the wire on ces SF from entering the sleeve too far Do not twist the SESTE iiis wires as that will cause less contact area with the metal insert and reduce its capacity e After both wires are inserted apply a firm crimp just once on each side of the notch Multiple crimpings will actually weaken the connection Crimping tools will either be color coded or labeled by wire size to ensure the correct jaws are used on the tool Do not use pliers vise grips or other improper tools for crimping as these will damage the sleeve e Use a proper heating tool such as a shielded butane torch to melt the splice always working from the center of the sleeve o
77. l prevent driver programmed information from being lost radio station presets clock etc as well as possibly avoiding driveability problems associated with the control modules having to relearn information It can take up to one hundred miles of driving to relearn everything ideal ignition timing injector pulse width etc and operate normally The service manual provides the procedure for Battery Electrical Drain Parasitic Load testing using an ammeter in series and the special tool Follow the procedure exactly to avoid damage to the vehicle or meter Special Tool Parasitic Draw Test Follow the Procedure Exactly Page 54 of 88 MLR Electrical Study Guide 2013 Melior Inc Phantom Drains A phantom drain is an abnormal parasitic load caused by a component such as a trunk or glove box light bulb that stays on all the time This can be caused by misadjustment a bad switch or a short A phantom drain can draw up to several amps and will discharge the battery faster than a normal parasitic load Once it has been established that there is an excessive parasitic load the problem can be isolated by pulling fuses or disabling circuits until the circuit causing the drain is identified The fuse is then replaced and each component on that circuit is checked one at a time until the trouble is isolated It may be necessary to remove the fuse for the interior lights so the doors can be opened Self Discharging When a battery is stor
78. ld result in personal injury or death damage to electrical system or improper diagnostic Using a Test Light to Test Electrical Circuits CAUTION Never use a test light to test low voltage circuit Doing so may damage or destroy expensive electronic components On vehicles equipped with electronic control modules only use a test light when directed by a manufacture diagnostics test procedure A test light is a useful and reliable tool when used correctly A test list can be used to test for open circuit closed circuits and short circuits In a closed circuit the test light will illuminate when connected to a circuit that has a current flowing on the power side On an open circuit a test light will not illuminate if there is no current flowing when connected after the opening in the circuit A test light can be used to test for a short circuit if connected in series with the short circuit Normal Circuit In this circuit the test light should illuminate when connected on the power side of the circult In this case a test light was able to prove the circuit Is working normally from the power source to the load TEST LIGHT TEST LIGHT Open Circuit In the circult the test light Is being used to diagnose an open power circult How TEST LIGHT ever the test light will iluminate at point A because there Is a complete path to that point Point The test light will not illuminate at
79. le Double Throw Multiple PoleMultiple Momentary Throw Page 16 of 88 MLR Electrical Study Guide 2013 Melior Inc Relays Another type of switch is a relay As was discussed earlier a relay uses a small amount of current to control a larger amount of current flow Relays can be either normally open or normally closed Relays are constructed using an iron core an electromagnetic coil and an armature moveable contact set Relays that are controlled electronically such as those controlled by the PCM Powertrain Control Module are usually ground controlled Relays that are controlled by the operator such as the headlight relay are normally Relay Symbol power controlled Relays normally follow a common wiring scheme The main difference between a relay and solenoid is that a relay controls an electrical output whereas a solenoid controls a mechanical output Relay Diagram Construction POWER CIRCUIT ARMATURE Power Controlled Relay Ground Controlled Relay Other Components Here are a few additional common components and their symbols Bulbs Automotive bulbs are used for internal and external illumination and are often used as warning lights 3 Automotive bulbs are often similar in design however due to varying resistances of bulb elements it s Single Element Bulb Dual Element Bulb important to use the correct replacement bulb Page 17 of 88 MILR Electrical Study Guide
80. ley as shown Any belt that bottoms out must be replaced One method of checking for slippage is to firmly grasp the generator by the fan blades or pulley and attempt to rotate it If the pulley can be rotated by hand excessive slippage is present and must be corrected Do not overtighten a worn out or oily belt as this can ruin the bearings in the alternator or other accessories Proper Fit Warn Out Listen for unusual noises from the alternator A buzzing grinding or rattling can indicate mechanical problems such as a bad bearing or broken internal parts A loud whining can be caused by bad diodes or overcharging Page 84 of 88 MILR Electrical Study Guide 2013 Melior Inc The system to the right uses a flat serpentine belt with an automatic self tensioner A spring inside the unit applies the proper tension to the belt Electrical Testing For accurate electrical testing the vehicle must have a known good sufficiently charged battery A sulfated shorted or dead battery can cause misleading test results Connect a voltmeter across the battery with the engine running at about 2000 rom for a quick functional check of the alternator A no load voltage or open circuit voltage of approximately 13 2 to 14 7 volts indicates some output is being generated An output lower than 13 2 V indicates battery voltage only If battery voltage is indicated check wiring harnesses and generator connections Jiggle the
81. llows 1 Turn headlamps off and allow them to cool completely 2 After they have cooled turn them on for 15 minutes 3 After 15 minutes turn them off and on quickly 10 times in about a 15 second period Page 41 of 88 MLR Electrical Study Guide 2013 Melior Inc 4 If one headlamp does not obtain full brightness or burn dim the HID headlamp is nearing the end of its useful life It is recommended by manufacture that HID headlight be replaced in pairs Over time HID headlight will not illuminate as they once did when they were new Using an electrical wiring diagram A wiring diagram is an extremely valuable tool when diagnosing an electrical concern in any type of equipment or vehicle The proper use of a wiring diagram will reduce diagnostic time There are several different methods advanced by different automotive manufactures and textbook authors Some recommend always starting at the power source when testing an electrical circuit Other manufactures teach starting at the malfunctioning component and backwards testing the circuit Still other recommends starting at the fuse box or relay if the circuit is relay controlled Before beginning diagnostic on an electrical circuit it is recommended that a technician review circuit operation Some manufacture used slightly different schematic symbols to identify components Note Always follow manufacture diagnostic procedure when diagnosing electrical systems Failure to do so cou
82. ltage is i controlled by the PCM Carefully 1 l en examine this schematic and the Note control The charge lamp output from A module jl to IPC is provided by data bus PCM components Note the battery thermister which provides battery temperature information to the system for voltage corrections Generator field input F terminal Generator feedback r thermistor C eal Si with lower or higher voltage or stopped generator Regulator Je state 1E 7 E vte iny input sensing YY input Field 9 rotor Chapter 2 Charging System Diagnosis and Service While there are relatively few components involved in the charging system they are interdependent and troubleshooting should be systematic and methodical to ensure an accurate diagnosis Refer to the appropriate service material for diagnostic flow charts procedures and specifications Visual and Mechanical Inspection Begin by checking that all battery terminal and alternator connections are clean and tight Check the drive belt condition and tension Look for glazing or oil on the V Belt Fit belt which may cause slippage Even a small amount of slippage may Belt prevent the battery from receiving an adequate charge On V belt gi applications check for proper fit and alignment The belt should be driven by the sides of the V and should not ride low in the pulley nor contact the bottom of the pul
83. ly the charging current it can accept at the charger s voltage Regardless of which type of charger is used the procedures outlined here must be followed closely to prevent undercharging or overcharging and battery damage on the charging line Series Charging Batteries on a charging line may vary in age capacity or size state of charge and type For this reason and other considerations series charging is not recommended The procedure has been included for your information and in case you should be required to use a series charger Page 64 of 88 MLR Electrical Study Guide 2013 Melior Inc Batteries on a series charger should be closely monitored for spewing Series Charging gassing high temperature or voltage of over 15 5 volts To charge batteries in series Connect all the batteries negative terminal to positive terminal using single jumper cables Connect the charger to the remaining positive terminal on one battery and the remaining negative terminal on the other battery to complete the series circuit as shown in the illustration Connect the charger to a power source Set the charger to maintain a charging rate of 5 to 10 amps Monitor each battery and the charging rate every 30 minutes Turn off the charger and disconnect any recharged battery Parallel Charging When charging batteries in parallel the current rate is dependent on the voltage setting Most parallel chargers have a number of switches that
84. n all directions Avoid creating sparks around a battery e The ground terminal of a battery should always be disconnected first and reconnected last e Connect battery chargers to a battery before plugging in the charger e When jump starting a vehicle follow the proper procedure Do not connect the jumper cable to the negative battery terminal of the vehicle you are jump starting e Do not attempt to charge jump start or load test a battery with a broken or loose post a cracked case or one in which the electrolyte is frozen Page 2 of 88 MLR Electrical Study Guide 2013 Melior Inc e Never hammer on a battery terminal or cable end or attempt to remove a cable by prying To avoid damage to the battery or terminals and possible personal injury use a clamp spreading tool if the clamp doesn t seat at the bottom of the post and use a cable clamp puller to remove stubborn clamps Avoid contact with the white flaky or powdery corrosion that builds up around battery terminals and trays This substance is sulfate and or sulfide it is corrosive and can cause chemical burns e Accidental shorting of the positive battery terminal or any system voltage source to ground with a tool or metal object can cause severe burns Metal jewelry can be heated to its melting point in seconds Even a brief short of this nature can damage the PCM and other electronic components You should know the locations of fire extinguishers and the first aid k
85. n cranking motor to flywheel and pinion 4 Cranking motor turns Pinion not engaged Realign cranking motor to flywheel but engine doesn t Replace defective drive Some medium duty diesel applications are equipped with starter overcrank protection These starter motors have a built in thermostat that opens the circuit to the solenoid if the starter gets too hot The thermostat closes the circuit when the starter cools An open in the thermostat will cause a no start condition The thermostat terminals are on the front of the starter and should show continuity when with checked an ohmmeter Testing Current Draw Testing A starter current draw test can quickly tell you the condition of Current Draw Testing the starter motor and other system components Current draw PUTT should not be higher or much lower than specifications so To perform a current draw test 1 Disable fuel delivery system to prevent the engine from starting Refer to the service manual to find the procedure for the application on which you are working 2 Connect an ammeter in series between the negative battery terminal and cable end or clamp the ammeter s inductive pickup around the negative battery cable A meter rated to 500 or 600 amps is recommended Do not exceed the meter s range If using a hand held DVOM be sure to use the correct high current shunt to avoid damage to the meter Page 72 of 88 MLR Electrical Study Guide 2013 Melior
86. nc Drain lines are less commonly used than the previous Drain Line Diagram two but they are gaining popularity A Drain line is a PCM bare non insulated wire that travels the length of a cable with other circuit wires but is connected to ground only on the module end Drains act like antennas that receive spurious electrical noise and transfer it to ground It is important for technicians to remember to not cut the drain wire or connect it to any other wire Sensor Wire Sizes In the automotive industry there are two scales used to measure the sizes of wires American Wire Gauge AWG and metric American Wire Gauge is a system that has been in use for decades but is quickly losing out to the metric standard The AWG scale uses a series of even numbers to denote the non insulated diameter of a wire In the AWG system the larger the rating number the smaller the wire and the lower its current carrying capability The metric scale for measuring wire is based on the cross sectional area of a non insulated wire expressed in square millimeters Unlike the AWG system however a larger number in the metric scale translates into a larger wire and a greater current capacity Both scales and their respective sizes are shown in the following chart Length vs Resistance All wires exhibit increased resistance as their Wire Length versus Current Capacity length is increased Therefore the longer a wire needs to be the larg
87. nd Brushes Rotor A generator rotor is rotating a magnetic field assembly mounted on a shaft that rides in bearings located in the front and rear of the generator case Brushes The spring loaded carbon brushes are in constant contact with the slip rings The slip rings are insulated from the rotor shaft and are connected to opposite ends of the rotor windings One of the brushes is connected to system voltage and the other to an alternating ground As a result of the applied voltage a variable current flows through the field windings and creates a variable magnetic field Note the alternating N and S fingers of the pole pieces in the illustration A Rotor Core of Field Windings Interlacing Fingers or Claws THE ROTOR IS COMPOSED OF ist An Iron Core m Tis Cs _ Ssesreenss A Shaft UP SSS quis in Two Copper Slip Rings Te er re Be mt Two Pole Pieces with Roe atl HU Brushes eo Brush Holder Cy E Slip Rings The brushes in an AC generator tend to be much smaller than brushes in starter motors since they carry only field current to the rotating field Stator In an alternator the stationary winding assembly is called a stator A stator consists of three windings called phases assembled onto an iron frame The currents that are induced in each winding by the rotor are added to produce the alternator s total output current As the alternating N and S poles of the rotor pa
88. o a certain The float will rise less or not at allin a level indicating the state of charge of the cell A reading discharged battery is taken and noted and each cell is checked in this manner Here are some guidelines for using a hydrometer Conventional Hydrometer e Remember electrolyte is acidic Be careful and avoid allowing the hydrometer to drip Release the electrolyte back into the battery slowly e The float should be lifted free and not touch the sides or bottom of the barrel e Take the reading with your eye level to the surface of the fluid e lf there is a difference of 050 between the lowest and highest readings or if all readings are below 1 225 recharge the battery e f after recharging the battery there is still a 050 difference between the highest and lowest reading or there is still a reading below 1 225 replace the battery e lf the battery passes this test proceed with a load test Frequently five cells will show good readings in the 1 250 to 1 270 range with one cell showing a very low reading or not moving the float at all Commonly called a dead cell this usually indicates a short No further testing is necessary the battery must be replaced Page 58 of 88 MILR Electrical Study Guide 2013 Melior Inc Drawing Electrolyte into the Hydrometer Electrolyte t i Level Float Suspended in Electrolyte e Last Cell Doesn t Float Buoyant
89. o much heat for too long a period of time can cause a bad connection Insure that your solder is smooth and doesn t have any points that might stick through the tape Never solder a powered circuit especially with an electric soldering iron Do not wiggle the wires or terminals until the solder has cooled completely To do so may result in a cold solder joint that could adversely affect the connection After the solder has cooled apply electrical tape to splices to prevent inadvertent contact with other metal surfaces Insure that your tape wrap is smooth and does not leave any flags which may cause the tape to come loose Although tape wrap sealing is acceptable the seal of choice is heat shrink tube It is similar to the splice cap but is a different style of repair You manually solder the connection first then slide the shrink tube over the repair and then shrink the tube with a heat source to collapse the tube NOMINAL a 100 Solder Coverage of Core and Clip Solder Fillets Between Core Less than 100 Solder Missing Solder in Clip Burned Insulation or Excess Coverage Window Solder Sticking to Insulation Must Pass Pull After Solder Some Wire Exposed Due to Can be Covered by Requirements Insulation Shrinkage Insulating Covering Must have Solder Fillets Between Core and Clip Not Required for Clip P N s 5290433 and 2962985 Page 30 of 88 MLR Electr
90. omobiles generally use what is classified as a wet cell lead acid battery Batteries produce current through a chemical reaction between the active materials of the plates and sulfuric acid in the electrolyte Throughout the life of a battery it is either Complete Discharge charging or discharging When a battery is supplying current to accessories or to the While completely discharging an automotive starter it is said to be discharging When the battery does not ruin a battery that is in good condition it may shorten the life of the battery engine is running at sufficient speed the generator carries the electrical load and charges the battery and both are said to be charging A battery is discharging when e The engine is not running parasitic loads or self discharging e The engine is running at a low rpm with conditions of high electrical demand e There is a fault in the charging system A battery that is nearly or completely discharged is commonly said to be dead flat or run down A battery in this condition should be recharged to full capacity to provide proper service Although a generator will charge a battery it is not designed as a battery charger Requiring a generator to recharge a completely dead battery may cause overheating and damage to the generator Page 45 of 88 MILR Electrical Study Guide 2013 Melior Inc Unlike deep cycle batteries used in some RV and marine applications an au
91. on with a screwdriver If the pinion does not turn To minimize the risk of eye injury wear freely the motor may have binding bearings a bent safety glasses when performing this test armature shaft or other internal problems If the pinion turns freely the starter can be no load tested A no load test may point to specific defects in the motor and No Load Test is also useful for testing new or rebuilt units for proper operation prior to installation on the vehicle To perform a no load test make the connections as shown When the switch is closed compare the current and voltage readings with the specifications A higher voltage will yield higher rom with the current remaining essentially unchanged An even simpler form of this test can be used to verify that a unit will operate This is especially useful for checking new or rebuilt units before installation The starter motor is held firmly by a suitable means and connected to a battery with jumper cables and a jumper wire across the solenoid Connect the Page 74 of 88 MLR Electrical Study Guide 2013 Melior Inc positive cable to the solenoid battery terminal first and then connect the negative cable to a suitable ground on the starter otherwise arcing may damage the threads on the terminal The solenoid will kick the pinion out and the motor will spin With experience the sound and pitch of the starter at free speed can be used to estimate starter condition
92. operties In our study of electricity we will apply measure and calculate four different units Voltage Current Resistance and Power Voltage Voltage can easily be described as electrical pressure A comparison to a household water hose will be useful in SENSE discussing voltage If you have a water hose with a Voltage is defined as electrical pressure closed nozzle on the end and the spigot has been opened there is water pressure in the hose even though no water is able to escape through the nozzle What actually causes voltage can be understood by recalling the earlier discussion about free electrons When there are more free electrons in one place as compared to another such as between the positive and negative plates of a car battery there is said to be a difference of potential or Voltage The greater the difference between the number of electrons on one battery plate and the number on the other plate the higher the voltage A dead battery has the same number of electrons on the positive plates as on the negative plates As we deal with electricity we will see that this electrical pressure has a number of different names which all mean the same They are e Voltage or V e Electrical Potential e Potential Difference e Electromotive Force or EMF or E For the purposes of this course we will use the term Voltage and either the V or E designation Also remember that voltage is merely a pushing force and do
93. ore first since crimping the insulation first will cause the strands to spread and make core crimping more difficult Page 31 of 88 MLR Electrical Study Guide 2013 Melior Inc e Next select the correct anvil to crimp the insulation wings if the terminal uses an individual insulator slide it into place first This crimp is used to hold the terminal in place rather than for electrical contact and therefore will not need to be quite as firm as the core crimp e After crimping gently tug on the wire and Proper terminal to check for proper tension and Crimping Position apply solder if required Reinsert wire into MATING ENO WINGS INSULATION CABLE Wek un connector Chapter 5 Testing Series and Parallel Circuits Voltage Drop As explained earlier in this course voltage drop is like the pressure decrease in a hose with a crimp in it it is defined as the difference between the voltage on the inlet side of a device compared to the voltage on the outlet side Comparing that value to a written specification will assist the technician in determining the fault with the system Orifice Voltage Drop High Pressure Low Pressure Voltage drop is the difference in electrical ROH SE A BAK OS i pressure between the two sides of a device Higher Voltage Lower Voltage Voltage Drop Parallel Circuit Formulas Parallel Circuit Resistance To calculate total resistance in a series circuit
94. otate within a stationary magnetic field but in an AC generator the magnetic field rotates within a stationary conductor winding assembly Modern AC generators are commonly called alternators and today the terms generator and alternator are used interchangeably Charging System Modes of Operation This illustration shows a typical battery generator and electrical load configuration In this mode the generator is not producing current and the battery is supplying all of the available current This condition occurs when accessories are operating without the engine running and or during a charging system failure If this situation were allowed to continue for an extended period the battery would become discharged Battery and Generator Supplying Current This illustration shows both the battery and generator supplying current This situation occurs when the generator is not operating at a sufficient speed to meet the electrical demand and the battery is required to make up the difference A high electrical demand at idle could cause this condition This condition will also cause the battery to become discharged Page 78 of 88 MLR Electrical Study Guide 2013 Melior Inc Generator Supplying Current In this illustration the generator is operating at a sufficient speed to supply both adequate operating current and to recharge the battery The generator recharges the battery by creating a voltage high enough to
95. pear green dark or yellowish Page 57 of 88 MLR Electrical Study Guide 2013 Melior Inc e Green eye The battery is charged to at least 65 of Built In Hydrometer its specific gravity Some battery manufacturers consider this sufficient for testing e Dark eye The ball is not floating high enough to be seen indicating the battery is less than 65 charged This does not necessarily mean the battery is bad merely discharged The battery may be tested with an appropriate electronic tester but results may be inconclusive The battery must be recharged in order to perform conventional load testing e Yellowish eye clear The electrolyte level is low replace the battery Sometimes a gas bubble will Battery Explosion Risk cause a false yellow reading Tap the hydrometer imadtesitns chaming oriume cerctinge lightly with a small screwdriver handle or shake the battery with insufficient electrolyte or a battery gently and check it again Do not attempt to loose post poses an explosion risk charge or load test a battery with a yellow eye Conventional Hydrometers A conventional hydrometer works like an eyedropper or a turkey baster The battery caps are removed and the Hydrometer Float bulb is squeezed before immersing the pick up tube in TReH Cam e E a a ead the electrolyte When the bulb is gently released battery because the electrolyte is heavier electrolyte fills the tube and the float rises t
96. portant to explore these types in a basic manner at this point in order that we may be able to understand how to apply Ohm s law to a circuit e Series circuit e Parallel Circuit e Series parallel circuit A series circuit is a circuit that only provides one path for current to flow A parallel circuit provides more than one path for current to flow and a series parallel circuit is a combination of both types of circuits When using Ohm s law there are a few simple rules to remember When working with a series circuit E oi e Two or more electrical devices are required for a series circuit e Voltage changes the point of highest resistance will be the point of greatest voltage drop e Amperage remains the same e Total circuit resistance will equal the sum of all resistors or loads in the circuit e Any opening will disable the entire circuit SHEH Ay gt 80hm a 4 Ohm 3 When working with a parallel circuit a e Voltage remains the same at the input of each branch s first load device e Amperage changes the higher the branch resistance the less current flow in that branch e Total resistance will be less than any individual branch resistance e Any opening in an individual branch will not disable the entire circuit Two or more load devices are required for a parallel circuit C ia Page 22 of 88 MLR Electrical Study Guide 2013 Melior Inc Calculations for Circuits Series
97. r killed and property is damaged due to not following electrical safety rules and common sense Do yourself and others a favor Pay attention and use Safe practices Warning To avoid possible personal injury e Always follow all general safety guidelines for servicing motor vehicles with regards to electrical connections flammable or corrosive materials adequate ventilation jacking and supporting working around hot or moving parts proper use of parking brake gear selector wheel blocks and disabling fuel or ignition systems Refer to the equipment User s Manual and vehicle Service Manual for the operation you are performing e When making electrical measurements never exceed voltage or current limits as indicated for the equipment e Use extreme caution when working with circuits that have greater than 60 volts DC or 24 volts AC e Donot operate damaged equipment e Automotive batteries can explode and have enough power to arc weld Always respect the power of a battery even a dead battery The sulfuric acid in electrolyte is extremely corrosive and can cause severe chemical burns to the skin and eyes It will also damage painted surfaces and many other materials including clothing Always wear approved safety glasses when working around batteries and the use of rubber gloves is recommended when working with electrolyte Batteries release hydrogen and oxygen gasses When a battery explodes it can rupture the case and spray acid i
98. re Terminal Type a Measured made of lead a very soft Pound Inch Pound Foot Newton Meters metal Below are the Tapered terminal posts SAE 50 70 b n 4 6 lb ft 5 4 8 1 Nem torque specifications for Side terminals 90 180 Ib in 7 5 15 eft 10 0 20 0 Nem battery connections Stud terminals 120 180 Ib in 10 15 bf 13 5 20 0 Nem Unit 4 STARTING SYSTEMS Chapter 1 Starting System Components Starting System The starting system uses power from one or more batteries to spin a cranking motor starter When the Starting circuit is energized a pinion gear mounted to the shaft of the cranking motor engages with teeth on the flywheel and the engine is cranked for starting The components involved in the starting system include e Battery provides power to the cranking motor and ignition system e Ignition switch permits operator to control starting system operation Page 66 of 88 MLR Electrical Study Guide 2013 Melior Inc e Solenoid high current relay that permits connecting the battery to the cranking motor at a convenient physical location in the circuit Provides the movement for engaging the pinion gear to the flywheel e Starter high torque electric motor for cranking the engine Includes the drive mechanism for engaging the pinion gear with the flywheel e Battery cables wiring starter relay fusible links etc When the ignition key is turned to the START position a circuit to the solenoid
99. rm of output For instance light bulbs are rated in watts but have an output in lumens Audio speakers have an output based on how much air they move and resistors also rated in watts put out heat Electric motors as mentioned before are an exception in that they are rated in horsepower output rather than watts consumed Page 12 of 88 MLR Electrical Study Guide 2013 Melior Inc Power symbol P is expressed in Watts but can be converted to horsepower using the equation 1 Horsepower 746 Watts It is not as important for automotive technicians to calculate power as compared to voltage drop or amperage draw However there are circumstances when the amount of power consumed or produced is a concern Power Formula As mentioned earlier Power is not a direct measurement but rather the product of the voltage current and resistance To calculate the power consumed the following pie chart may be helpful Just like with Ohms law if any two variables are known you will be able to determine the other two P IxE or Watts Amps x Volts From this formula we can see that one Watt is equal to one Volt multiplied by one Amp We can also see that if either the voltage or current is increased then the power wattage also increases Likewise a decrease in either voltage or current causes a corresponding reduction in power As an example let s assume we have a device with 120 Volts applied and a Current of 10 Amps Using the
100. rminal applications 3 Follow the equipment instructions for connecting the inductive amp probe This usually involves installing the probe around the negative tester cable with the probe arrow pointing in the direction of current flow towards the machine The instructions may also direct you to zero the ammeter 4 Remove the surface charge by applying a 100 amp load for 10 seconds Wait 15 seconds to let the battery recover before testing 5 Apply a load of the battery s CCA rating using the tester s carbon pile 6 After 15 seconds note the voltage and remove the load 7 Measure or estimate the battery temperature and compare the voltage reading to the appropriate value on the chart At 70 F the voltage should not drop below 9 6 volts Useful Quick Checks To check for electrical leakage across the surface of the battery Checking for Electrical Leakage touch the positive probe of a voltmeter to the surface of the battery between the terminals and the negative probe to the E negative battery terminal lt re Any voltage reading indicates electrical leakage This test is most useful with top post batteries To check for a poor connection between the battery post and the cable clamp measure the voltage drop Disable the fuel system to prevent starting Probe the top of the positive post with the positive probe and probe the body of the clamp with the negative probe while cranking the engine A reading gre
101. rrent to control a larger contact current Inside a relay there is a coil of wire and one or more sets of contacts Applying a small current to the coil creates a magnetic field which pulls in the contact s and closes the circuit sending the larger controlled current to the load device eg fuel pump ECM etc Page 6 of 88 MILR Electrical Study Guide 2013 Melior Inc Because a relay uses a small amount of control circuit current to control the flow of a larger current it allows for the reduction of wire size throughout a vehicle and a corresponding decrease in weight Primarily there are two types of relays on today s vehicles They are known as Micro relays and Mini relays They have normally 4 pins or 5 pins But don t let the number of pins scare you They all work in the same way Relay The control side of the relay are pins 85 and 86 When power and ground are applied to these two terminals an electromagnetic field is created and a contact is pulled down When this contact is made it allows power waiting at pin 30 to go though the contact and out pin 87 to its destination There are variables but remember that pins 85 and 86 are married as the control side and pins 87 and 30 are the load or work side of the relay Pin 87A is normally used to control another portion of a system such as the l Engergized relay park control in windshield wipers Solenoids fuel injector A solenoid is an elec
102. rting power required may be 300 percent of normal e At 20 F only about 20 percent of the battery s power is available while the starting power required can be over 300 percent of normal At this point it is obvious that it is especially important to have clean tight connections and a fully charged battery in cold weather Keep in mind that cold temperatures have the same effect on charging rates that is it takes longer to recharge a battery in cold temperatures Excessive heat can also have an adverse effect on batteries Batteries will self discharge faster in a hot environment In addition higher compression engines require more current to start when they are hot Battery Ratings Cold Cranking Amps CCA Battery Temperature and Efficiency Battery Charge Engine Cranking 80 Requirement 0 45 65 100 50 100 200 300 _ 32 a The Cold Cranking Amps rating indicates how much current in amps a battery can provide for 30 seconds at 0 F while maintaining a minimum terminal voltage of at least 7 2 volts Battery CCA The CCA rating is the most important rating of a battery Page 50 of 88 MLR Electrical Study Guide 2013 Melior Inc This is the most important rating of a battery and it is used both in application specifications and in battery testing The cold cranking rating is usually provided on a label or stamped into the battery case Ratings from 3
103. s inside batteries This increases the time required for recharging The current accepted by the battery is very low at first As the battery warms up it accepts a higher current A deeply discharged battery may take quite a long time to recharge if charged in cold temperatures A temperature of 70 to 80 F is optimal Battery Size and Rating Larger more powerful batteries will take longer to recharge A battery with a high CCA rating may take more than twice as long to recharge as one with a low CCA rating The battery with the higher rating is denser having more plate material Charging Rate The more amps a charger can supply the faster it can recharge a battery Recharge time is often measured in ampere hours Look at the comparisons of recharging times for a battery that has been discharged at a rate of 20 amps for one hour 20 ampere hours e A charging rate of 20 amps will recharge the battery in one hour o 20amperes x 1 hour 20 ampere hours e A charging rate of 10 amps will recharge the battery in two hours o 10amperes x 2 hours 20 ampere hours e A charging rate of 5 amps will recharge the battery in 4 hours o 5amperes x 4 hours 20 ampere hours When fast charging a battery at a high rate 20 to 50 amps to bring it to a serviceable level of charge in the fastest possible High Rate Charging time it must be checked frequently Check to see that the Carefully monitor batteries when terminal voltage does not exceed 15
104. s must be taken when servicing hybrid electrical systems Not following the proper service procedures when servicing hybrid electrical systems can cause can cause personal injury and or damage to a hybrid electrical Series Hybrid A series hybrid vehicle uses both an electrical engine and a gasoline engine The system will operate on electrical power When the battery pack that operates the electrical engine runs low the gasoline engine will start to recharge the batteries The auxiliary battery is used for the low voltage system Precaustions should be followed before disconnecting the auxiliary battery Service Plug The service plug should be removed Failure to disconnect the and stored in a safe f high voltage service plug place while servicing before disconnecting the Zin w ae auxiliary battery Nega tive Cable could result in vehicle not entering READY state when bat tery is reconnected vehicle Page 43 of 88 MLR Electrical Study Guide 2013 Melior Inc Parallel Hybrid Vehicles can operate on battery power or gasoline When the battery pack is fully charged and driving j condition permit the vehicle operates on Parallel Hybrid vehicles Generate _ Generator 2 battery power alone When the battery canipamaets as arias E o C5 ba pack becomes discharged the gasoline l ha engine starts to provide power to drive the evel The Service Plug is rd 4 located at the High vehicle and
105. sconnecting any low voltage connectors at the inverter take safety all recommended safety precautions Some manufacture requires removing the high voltage service plug from the battery pack and waiting at least 10 minutes before disconnecting negative battery cable from the axillary 12 volt battery After disconnecting the 12 volt axillary battery it can be tested by following normal charging and testing procedure WARNING Failure to follow manufacture procedure can result in damage to the hybrid system or personal injury Page 44 of 88 MLR Electrical Study Guide 2013 Melior Inc Unit 3 AUTOMOTIVE BATTERIES Chapter 1 Batteries Overview Battery Function An automotive battery is an electrochemical device that converts electrical energy into chemical energy and stores it until needed When called upon the battery converts the stored chemical energy back into electrical energy The battery serves four purposes in an automobile e t supplies electricity to the accessories when the engine is not running e lt supplies high current to the starter and system voltage to the ignition system during cranking e t provides current to the electrical systems when the demand exceeds the output of the generator e tacts as a voltage stabilizer in the Electrical current flow is produced chemically by dissimilar plates in electrolyte solution electrical system POSITIVE ELECTROLYTE NEGATIVE Aut
106. se eae ee 51 Chapter 3 Charging and Replacement 0 0s c css1 e00s01 s COREE 60 Unit 4 STARTING SYSTEMS ccccceereeeccceessssessecssseessceeeeeee s e OOE 66 Chapter 1 Starting System Components 00ss 0000s0 1 e A 66 Chapter 2 Starting System Diagnosis and Service ccccccseseccecenseccceescccceensccceauscceseusececsesceesauneeess 71 Unit 5 CHARGING SYSTEMS cssssscsceseseeresseneeeessenseeeesesseees llama cr 77 Chapter 1 Charging System Components cccceeseceeeeeeeeees jo cococeee irae oan cuss ones Perey Spence ee 8 08 08 9 08 ee ee eee Chapter 2 Charging System Diagnosis and Service 66 2013 Melior Inc MLR Electrical Study Guide 2013 Melior Inc UNIT 1 ELECTRICAL THEORY Chapter 1 Electromagnetism Safety Warnings and Cautions Safety in the workplace is of great concern to all of us The Concepts you learn in each of the modules of this online training program will be applied using real test equipment on live electrical circuits in related projects It is imperative that you understand that electrical safety is extremely important The words ll caution warning and danger are related and mean this If you do not heed the safety message you can damage components equipment or injure or kill yourself or someone else The last thing you want to do is become a statistic Every year people are injured o
107. sealed battery with insufficient electrolyte must be replaced No testing is necessary do not attempt to test such a battery During your visual inspection also note the general condition and age of the battery Battery Life Despite marketing claims many batteries do not last the length of their extended prorated warranty period The normal lifetime of most batteries is from three to five years The date of manufacture is stamped into the battery case and or punched out of the label Most manufacturers use a date code with a letter corresponding to the month and a number corresponding to the last digit of the year For example a date code of A 1 means the battery was produced in January of 2001 Date Code April 2000 Coki Cranking Amps 525 Page 56 of 88 MLR Electrical Study Guide 2013 Melior Inc Open Circuit Voltage Open circuit voltage is the voltage in a battery without any loads connected Checking the open circuit voltage will give you a quick check of a battery s state of charge Remove the surface charge by turning on the Discharged Batteries May Still be Viable headlights for one minute then connect a voltmeter across the battery The reading should be 12 6 volts or Approximately 40 of condemned batteries more for a fully charged battery are fit for recharging and continued service A weak or discharged battery is often a symptom of a problem elsewhere in the vehicle Regardless of t
108. ses or the meter by using and incorrect configuration Check the fuses using the alert by putting the rotary dial in a non amperage position V or W and inserting a lead into each of the amperage input terminals Listen for the chirp indicating error Check both inputs as there are two fuses Make sure leads are not connected to other sources before inserting the leads this can prevent damage Scaling If a technician is trying to measure 10 000 000 ohms with the meter set on a 400 Q range the display will read OL since the Scaling maximum readable value is 400 ohms After switching the meter Always use the correct range to to the 40 mega Q range the display will show 10 00 Do not prevent reading errors confuse this with 10 ohms That is why it is so important to be aware of the scale currently being used especially if Auto Ranging is active The opposite condition can also be confusing in dealing with small values Imagine you are trying to measure 25 mA ona 40 A scale The meter bahay would basically display zero 00 03 However by display switching to a 4A 4000mA scale the readout now shows 0025 mA which is accurate 10 000 00 000 Meter ranged to display Megaohms A technician who is careful to use the correct unit setting Volt Amp Ohm and the right scale can Value too Meter ranged consistently rely on the meter information to assist aD eile in proper diagnosis Page 25 o
109. ss next to the stator coils three distinct AC voltage cycles are produced Stator Assembly Ss NNN ANN OES di wear y Sn i NAAN Quis N T mee Yau Page 80 of 88 MLR Electrical Study Guide 2013 Melior Inc Delta and Y The output from each stator winding is connected Delta and Y Connections in either a delta D or a Y configuration The Y configuration provides good voltage levels with acceptable current output for many applications The delta configuration produces good current at an acceptable voltage level and a high maximum output The delta configuration is the most common in automotive applications T ECN STATOR WIMDINGS AG OUTPUT pa Diodes and Diode Bridges Automotive circuitry operates on direct current DC and generators produce alternating current AC As a result we must convert the current from AC to DC before it can be used To accomplish this we use a series of diodes or rectifiers to make the conversion CATHODE DIODE CURRENT FLOW BLOCKED Diodes are electronic devices that only allow current to flow in one direction through the device By Diodes meonPerarine a series of diodes called a rectifier Raicdeneeme lecrenccommonanti nase bridge we can convert 3 phase AC to 3 phase DC an electrical check valve allowing current to flow through it in only one direction Waveforms A rectifier bridge also ref
110. st be 00 Dual path circuitry is preferred Symptoms Probable Cause 1 High pitched whine during cranking before engine fires Distance too great between starter but engine cranks and fires okay pinion and flywheel 2 High pitched whine after engine fires as key is being Distance too small between starter released Engine cranks and fires okay This intermittent pinion and flywheel Flywheel runout complaint is often diagnosed as cranking motor hang in or contributes to the intermittent nature solenoid weak 3 A loud whoop after the engine fires but while the Most probable cause is a defective cranking motor is still held engaged Sounds like a siren if the clutch A new clutch will often correct engine is revved while cranking motor is engaged this problem 4 A rumble growl or in severe cases a knock as the Most probable cause is a bent or cranking motor is coasting down to a stop after starting the unbalanced motor armature A new engine armature will often correct this problem Page 75 of 88 MLR Electrical Study Guide 2013 Melior Inc Pinion Clearance Insufficient clearance between the pinion and flywheel may also cause a grinding sound during cranking If improper clearance is suspected of causing an abnormal noise Remove the flywheel housing cover and check for obvious problems such as broken or damaged teeth on the flywheel and pinion a bent flywheel cracked starter housing or un
111. stances where magnets have become weak and caused operational problems such as a Crank Position Sensor that causes the engine to cut out at higher rom s or an ABS sensor that drops to zero while the vehicle is still moving These problems are most often caused by a drop in the flux density of the magnet itself but will not be seen in a resistance check of the wire winding Magnetic Force As electric current is passed through a wire it creates magnetic lines of force around the wire If that wire is wound into a coil it creates North and South Poles much like a permanent magnet except that it can be turned on and off and made stronger or weaker Because many metals are good magnetic conductors a core is often used in the center of the coil to enhance the strength of the electromagnet Most often the core is part of the design like the plunger in a starter solenoid or the pintle in a fuel injector If a number of different magnetic devices were cut open it would be apparent that the size of the wire and the number of turns around the core are not the same For various applications designers will change the wire size the number of turns the diameter of the coil the length of the coil and the applied current to get just the right amount of magnetic force needed for a particular use Page 5 of 88 MLR Electrical Study Guide 2013 Melior Inc Electromagnetic Induction We have already seen that we can create a magnetic field
112. sted shielded and ribbon cable Braided or CONDUCTOR E multi strand wires are made of copper or aluminum and are the most widely used because of their current carrying capacity and flexibility AONNE SOOS RIBBON CABLE Twisted or shielded wires are used in places INSULATION CABLE where electric noise may be present and the wires need to be protected The third type ribbon cable is used between electronic printed circuits or computers Shielding There are three forms of shielding used in most vehicles to protect the wires from receiving erroneous signals or other electric noise They are twisted wires Mylar tape and drain lines A twisted pair is simply two wires that have been wrapped around each other a certain number of times for each foot of cable length Any time a current is passed through a wire a magnetic field is created around the wire By twisting the wires together we can cause the magnetic fields to cancel each other out The second type of shield is Mylar tape Mylar is the same material used to make the shiny balloons and it has electrically conductive properties A shield made of Mylar can be either a reflector to prevent noise from reaching the wires or it can be connected to a negative point to absorb noise and send it to ground Any time a repair is made Mylar shields must be re wrapped and secured to maintain the noise protection Page 27 of 88 MLR Electrical Study Guide 2013 Melior I
113. swer 1 x is the inverse key is the addition key M is the Memory Add key MRC or MR is the Memory Recall key is the Division key and is the Equals key Page 33 of 88 MLR Electrical Study Guide 2013 Melior Inc Parallel Circuit Current Unlike series circuits where current is always the same parallel circuits can have a different amperage value for Parallel Circuit Current each branch in the circuit You will recall that the voltage The sum of the branch currents adds up drop is the same for parallel branches but if each branch Fig eran ET has a different resistance then Ohm s Law can be used to determine that the branches have different currents The total circuit current can then be found simply by adding the branch currents What is the total current for this circuit We know that since the two bulbs are in parallel their voltages are equal at 12V each amps The bulb on the left has a resistance of 60 and applying Ohm s Law we have Pe A l E R k Tail a9 Marker Light 2 amps 1 2 amp or ae o I 12V 60 t SO l 2 Amps Similarly the 24W right bulb has a current given by l E R2 or l 12V 240 SO l 5 Amps Total current is therefore h h l 2A 5A 2 5 Amps Now calculate the total current if the left bulb is 2Q and the right bulb is 120 Page 34 of 88 MILR Electrical Study Guide 2013 Melior Inc Series Parallel Circuits
114. t manufacturer s instructions regarding Side Terminal Adapters connection adapters and procedures Use the side terminal adapters that are provided with the equipment Do not substitute standard bolts for proper adapters as this may damage the battery terminals Do not use adapters that consist of a post of lead poured around a steel stud that screws into the battery terminal These adapters may cause high resistance and are a common cause of false test failures The connection inside the post can become faulty due to T Tae nsufficient Electrolyte Warning breakage or hidden sulfide build up between the stud and 4 z the lead post Acceptable adapters are usually brass or Do not attempt to load test a battery steel with insufficient electrolyte Observe all battery safety precautions Page 60 of 88 MLR Electrical Study Guide 2013 Melior Inc The Test To perform a load test 1 Verify that the battery is sufficiently charged for testing by Minimum Voltages observing the hydrometer eye or performing a hydrometer VOLTAGE TEMPERATURE TABLE check An alternate method is to perform step 4 and then check for open circuit battery voltage of at least 12 4 volts Minimum Temperature Voltage 2 Connect the test machine heavy clamps to the battery If the battery is in a vehicle connect to the terminals Rock the clamps back and forth to ensure a good bite on the terminals If not in a vehicle install adapters side te
115. ter replacement is a straightforward affair Procedures are in the service manual e Be sure to disconnect the negative battery cable before you begin e Re install any heat shields or support brackets e Starter mounting bolts are hardened to withstand the repeated torque produced by the starter motor Do not replace them with standard hardware e Itis much easier to make the solenoid connections before mounting the starter to the engine e Avoid allowing the starter to hang from the cables In many cases it may be more practical for both you and the customer to replace the starter and solenoid as a unit This is a good preventive maintenance practice because trouble with one component may foretell trouble with the other Starter Motor Repair The service manual contains detailed procedures and specifications for repair and rebuilding of starter motors Again this requires a judgment call and may not be practical With some units rebuilding is not recommended Check the service manual Unit 5 CHARGING SYSTEMS Chapter 1 Charging System Components The charging system uses power from the engine to keep the battery fully charged and supply the vehicle s electrical needs when the engine is running Major components of the charging system include e Generator generates electrical power to recharge the battery Supplies electrical needs of the vehicle s accessories e Voltage regulator an electronic device that sets an upper l
116. the other is connected to the starter thus completing the circuit By this time the pinion is fully engaged with the starter and cranking begins Observe the shift lever and its link to the solenoid in this illustration Flywheel Starting Motor i Sarai iiaii Overrunning Clutch Solenoid and Drive Operation Page 68 of 88 MILR Electrical Study Guide 2013 Melior Inc Solenoid Pull in Winding and Hold in Winding Some solenoids have two separate windings a pull in winding and a hold in winding The pull in winding has many turns of wire and the hold in winding has the same number of turns of smaller wire The illustration shows both windings As the ignition is turned to START current flows from the battery to the S terminal on the solenoid and through the hold in winding to ground Current also flows through the pull in winding to the solenoid M terminal and through the motor windings to ground When the solenoid contacts are connected there is equal voltage on both sides of the pull in coil thus no current flows through that branch of the circuit Solenoid Windings PULL IN WINDING PLUNGER AND SHIFT LEVER NOT A PART OF SOLENOID l PLUNGER Fl ai i g J I i E E Lee cee be PULLAN CRANKING MOTOR To BATTERY WINDING Diagnostically if a hold in winding fails the pinion will engage repeatedly but it will not remain engaged Likewise a
117. tomotive battery is designed to remain at or near a full state of charge and not to be completely discharged Battery Construction A battery is made up of individual cells electrically connected in series for a cumulative voltage effect Each battery cell contains an element made up of positive and negative plates separators and connecting straps Each plate consists of a stiff mesh grid of a lead alloy coated with porous lead on the negative plates and lead peroxide or lead dioxide on the positive plates A strap of lead connects the negative plates to form a group and another strap connects the positive plate group On each end of the battery the straps are extended to form battery terminals or posts The plates are submerged in an electrolyte solution Battery cells are housed in a durable vented Cell Divider Negative Strap Positive Strap Grid Porous Lead Separator Terminal Covers plastic case and have terminals on the top top post or side side terminal Many aftermarket batteries are equipped with both types of terminal arrangements When installing batteries equipped for both top and side terminal arrangements leave the plastic covers in place on the unused terminals to prevent corrosion or accidental shorting Negative battery cables are usually grounded to the engine block On some applications a small pigtail wire also connects the negative terminal to the vehi
118. tromagnetic device that uses applied current to produce lateral back and forth motion Solenoids such as fuel injectors and transmission shift valves have a movable metal core inside the coil As current is applied to a coil the electromagnetic field it produces either pushes or pulls the core and opens or closes a valve or engages a starter drive The terms relay and solenoid are sometimes used interchangeably but in fact they are two different things Motors Electric motors also work on the principles of electromagnetism but unlike relays or solenoids their function is to produce rotary spinning motion Motors have two primary components an Armature or rotating element and a stationary Field Coil Motors can have permanent magnet armatures with wound field coils permanent magnet field coils with wound armatures or have both the armatures and field coils wound Permanent magnet armature motors are used in Alternating Current applications and are not common in automotive applications In a DC electric motor voltage is applied to the armature winding through a pair of carbon brushes and a split ring called a commutator The commutator has the effect of alternately changing the poles of the armature coil from north to south and back again for each half revolution of the armature For example let s assume that a point on the outer Field Coil has a north orientation The half of the armature that has a south polarity would be attracted
119. tructure The copper atom has 29 electrons around its nucleus located in different layers or shells around Atom Info the nucleus two in the first shell eight in the 1 or 2 valence electrons are conductors second and 18 in the third shell for a total of 28 3 4 or 5 valence electrons are semiconductors That leaves just one electron in the outer shell or 6 7 or 8 valence electrons are insulators Valence shell and this single electron is the one that does all of the electrical work Atoms that have WEG Meo arate one or two electrons in the valence shell are called Electrical force is applied to valence electrons which conductors They include copper gold silver causes them to move through wires aluminum nickel zinc and others That is why they are used to make wire Atoms with a large number of electrons in the outer shell are called insulators and include rubber plastics etc Those atoms that have around four electrons in the valence shell are called semiconductors Semiconductors are used to make electronic components such as transistors which will be discussed in later modules At this point you may be asking So what does this have to do with electricity Very simple really Magnetism Another electrical characteristic we ll use in a later section is Magnetism Magnetism or Electromagnetism Electromagnets is also caused by the movement of electrons in a wire An electromagnet is created when a and is the proper
120. ty that makes generators starters current is run through a wound wire blower motors EGR valves and many other actuators Magnetism work Magnetism is used to convert electrical energy to mechanical energy or Magnetism is used extensively in automotive applications i mechanical energy to electrical energy to convert electrical energy to mechanical energy or conversely to change mechanical energy to electrical energy For instance if we apply electrical current to certain devices we can create lateral straight line motion such as in the starter solenoid to engage the starter drive or to open fuel injectors Still other components will use applied electricity to produce rotary spinning motion as is the case with fuel pumps and starter motors Generators however use magnetism to change motion belt driven to electrical output In the automotive field there are two types of magnets used They are e Permanent magnets e Electromagnets Permanent Magnets We are all familiar with permanent magnets those gray colored devices usually made in bar or horseshoe shapes It s likely most of us have a number of permanent magnets attached to our refrigerators holding up out of date notes and drawings In cars and trucks we will find permanent magnets in Crank Position Sensors distributor and distributorless types Cam Position Sensors ABS sensors some fuel pumps Vehicle Speed sensors and new style starters Page 4 of 88
121. urned fuse or fusible link e Loose starter or solenoid mounting bolts e Loose starter cable connection s e Bad or misadjust PNP or CPP switch e Ignition switch problems tumbler actuator or contacts e Theft deterrent system active e Bad cranking motor The service manual provides detailed diagnostic flow charts procedures and specifications We will present some general testing guidelines here Common Starting System Problems This chart addresses some common starting system problems Result Possible Cause Problem Source 1 Engine cranks slowly but does not start Very low temperature Battery must be fully charged engine wiring and starting motor in good condition Install proper cables Undersized battery cables Install proper cables Cranking motor defective Test cranking motor Mechanical trouble in Check engine engine Page 71 of 88 MLR Electrical Study Guide 2013 Melior Inc Result Possible Cause Problem Source 2 Solenoid plunger Low battery loose or corroded Check battery clean and tighten chatters terminals terminals Hold in winding of solenoid open Replace solenoid 3 Pinion disengages Sticky solenoid plunger Clean and free plunger slowly after starting Overrunning clutch sticks on Clean armature shaft and clutch armature shaft sleeve Overrunning clutch defective Replace clutch Shift lever return spring weak Install a new spring Tight alignment between flywheel Realig
122. urrent Direct current always flows in the same direction ina Direct current always flows in the same circuit whereas alternating current flows in one direction direction then reverses itself and moves in the opposite Alternate EO E ease ET direction Batteries and other steady state devices produce Volts DC We will also see what is referred to as 12 Volts DC Pulsating DC Pulsating DC is often incorrectly called AC although it is merely DC with a varying voltage Technicians will find that the vast majority of automotive circuits operate on DC Alternators and wheel speed sensors produce AC current In order for a current to be AC the current flow in a circuit must actually change direction Resistance Resistance is anything that opposes the flow of electrons As the resistance in a circuit is decreased the amount of current Resistance increases and as the resistance increases the current decreases Resistance is anything that Comparing this once again to our water hose analogy we find ae opposes the flow of electrons that if we use a larger diameter hose less resistance we will carry more water more current Conversely a smaller hose higher resistance carries less water lower current Some resistance is necessary in any electrical application as it is used to convert electrical energy to other forms such as heat defogger grids or light and to limit circuit current Those materials with low
123. usual tooth wear we 0s MORE THAN ONE Mark the flywheel to identify the high point i ans of tooth runout To do this start the engine and carefully touch the outside diameter of the rotating flywheel with chalk or a crayon Turn off the engine and disconnect the negative Flywheel to Pinion Clearance battery terminal to prevent inadvertent cranking of the engine Rotate the flywheel so that the marked teeth are in the cranking motor pinion gear area Move the pinion into mesh with the flywheel Some applications provide a hole in the bottom of the starter housing for inserting a screwdriver to do this illustration WIRE GAUGE Turn the flywheel if necessary so that a pinion tooth is centered directly between two flywheel teeth illustration Check the clearance with a wire gauge or an Allen wrench and compare to specs Clearance is generally between 020 to 125 inches On some applications pinion gear clearance can be corrected with shims To increase the clearance install shim s to contact both starter motor mounting pads as shown in the illustrations When replacing a starter motor always re install any original shims Shimming is not recommended on diesel applications Page 76 of 88 MLR Electrical Study Guide 2013 Melior Inc z Engine block Starter shim N Starter DAR Spy Starter mounting bolts Flywheel Starter Replacement and Repair Star
124. utward A proper seal will allow a small amount of glue to seep out of each end Cigarette lighters propane torches and soldering irons are not adequate for heating splice sleeves since they are too hot and will make the connection brittle Page 29 of 88 MLR Electrical Study Guide 2013 Melior Inc Soldering Soldering can be used if two or more wires need to be joined Taping Standards without terminals a splice or to insure a better electrical g connection between wires and terminals When properly applied solder will fill all of the air cavities in wires and permit better metal to metal connection Soldering done improperly however results in bad connections melted insulation and improper circuit operation Some recommendations for soldering Refer to this chart for acceptable standards for soldering GOOD Rolled Choose a soldering iron or torch with enough heat to do the job but not enough to damage smaller wires Soldering irons are usually rated in watts Apply some solder to the tip and wipe it clean This is called tinning and helps to transfer heat to your work Apply heat directly to the terminal or splice clip and feed the solder into the connection as the heat transfers to the wires Do not use an excessive amount of solder Too much may not allow pins to fit into the connector cavities and it also just looks messy Do not allow the soldering iron to burn the connection or insulation to
125. way overheating of charging components can be avoided This graph displays the temperature voltage curve for two typical applications Typical Diode Bridge ae REGULATOR LIMIT GENERATOR VOLTAGE S TERMINAL VOLTAGE BATTERY SENSE Page 82 of 88 MLR Electrical Study Guide 2013 Melior Inc Duty Cycle In order to achieve a regulated system voltage a voltage Voltage Regulator regulator will switch the field rotor current on and off ata fixed frequency of about 400 cycles per second System The voltage regulator controls the voltage is then controlled by varying the on off time of the magnetic field strength by rapidly turning field current For example at low speeds the field may be the field current on and off turned on 90 percent of the time and off 10 percent of the time This yields a relatively high average field current which when combined with the low generator speed or high electrical demand produces the desired system voltage As generator speed increases less field current may be GENERATOR FIELD CURRENT needed to generate the desired system voltage and the duty cycle changes to reduce the average field current AVERAGE on At high engine speeds the regulator may be on for only P ierde 10 percent of the time and off 90 percent of the time The duty cycle will change as operating factors and TIME loads change to provide just the right amount of field current to produce the necess
126. we can simply add the values of the individual resistances Ina parallel circuit it is a little more involved For example Parallel Circuit Resistance oo l Parallel circuit total resistance must be less in a circuit with three branches having 10 20 and 30 a EE E E E EAA ohms respectively we know the total resistance must ees Spee be less than 10 ohms the value of the smallest branch rather than the 60 ohms we would have in a series circuit Page 32 of 88 MLR Electrical Study Guide 2013 Melior Inc The sum of the reciprocals can also be expressed as 1 R 1 R 1 R gt 1 R3 1 R Fers Applying our values we have 1 R 10 050 0330 1 R 1830 R 1 1830 Ry 5 460 The Windows calculator on your computer can be used to make these calculations You can open the Windows calculator by clicking on Start and then Run Type the word calc without the quotes in the space provided and then click the OK button Try both of these methods using our example numbers of 10 20 and 300 If your calculator has a 1 x inverse key the formula can be entered by pressing the calculator keys shown in parentheses in order as follows R 1 x R3 1 x R 1 x 1 x answer If no inverse key is available then figure the resistances by pressing the calculator keys shown in parentheses in order as follows 1 Ri M 1 R2 M 1 R3 M 1 MRC or MR an
127. wires while observing the voltmeter If the system begins charging you have located a wiring problem You may notice a whining as the generator begins to charge and a brief loading of the engine before the PCM adjusts the idle speed Safety Precautions Never short or ground any charging system terminal unless instructed to do so by the service manual Never remove the battery from the circuit with the engine running Page 85 of 88 MLR Electrical Study Guide 2013 Melior Inc Never remove the battery from the circuit with the engine running The resulting voltage spike may ruin the PCM or other electronic components Never short or ground any charging system terminal unless instructed to do so by the service manual On older vehicles a common diagnostic method was to bypass the regulator and apply full system voltage to the field circuit in order to determine whether the alternator was capable of charging Bypassing in this manner causes the alternator to begin unregulated charging which can damage electronic components Scan Tools and Scopes For many vehicles a scan tool can be useful in diagnosing charging Scan Tool systems Scan tools can display charging rate battery temperature and other useful data Oscilloscopes can be used to display voltage waveforms to diagnose diode failures that voltmeters cannot detect Study the waveform examples on the following screens and refer to the scan tool instructions

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