Home

Fault Diagnosis Service Manual

1. TO BALLAST RESISTOR Fig 39 Voltage at terminal of coil contacts open Fig 40 Distributor earth TEST 6 Voltage at Terminal of Coil Contacts Closed When all connections are re made the voltmeter is left connected as in Test 4 i e between the coil ve terminal and a good earth Fig 41 The contact points are closed by rotating the engine When the ignition is switched on a zero reading should be obtained If the voltmeter registers a voltage it is due to one of the following faults 1 Dirty or oily contacts 2 Bad earth connection for instance between the distributor shank and the engine block or the flexible lead from the contact plate to earth 3 Contacts not closing properly 4 A high resistance in the circuit from the coil to the C B on the distributor 5 Broken flexible lead between the distributor L T terminal and the contact breaker terminal post 6 Open circuit coil to distributor lead Tests for the secondary H T circuit are identical to those for conventional systems as described in the previous section Note Static and stroboscopic timing is described at the end of this chapter Fig 41 Voltage at terminal of coil contacts closed Page 21 ignition switch starter solenoid battery Y Fig 42 Typical OPUS system INTRODUCTION The OPUS Oscillating pick up system Fig 42 is a
2. 45 23580 60 23633 24 23 Fig 73 Checking alternator maximum output Page 34 A zero or low reading indicates that the alternator stator and or diode circuit is faulty TEST 8 Checking Voltage Regulator Setting 4TR The 4TR voltage regulator is checked at normal operating temperatures on closed circuit conditions using a well charged battery Run cold engine at charging speed for at least 8 minutes a With ammeter in the main output cable connect a voltmeter across the battery terminals See Fig 74 b Switch on side lamps start and run engine at approx 3 000 rev min c Ensure that the voltage regulator is regulating The ammeter must indicate less than 10A and should not increase with speed d Voltmeter reading should be between the limits 10 11AC Alternators Voltage Regulator Setting Volts 139 14 4 27 9 28 3 12V systems 24V systems Note l A low reading indicates a faulty 4TR unit 2 If the reading is higher than the limits or un stable the test should be repeated with the voltmeter connected across the and terminals of the 4TR unit 3 A high reading indicates a faulty 4TR unit A correct reading denotes a high resistance in the sensing circuit which must be located and remedied 4 An unstable reading is due either to a high resistance in the circuit which must be checked or a faulty 4TR unit SWITCH TO STARTER
3. Wi white lead and a good earth The voltmeter should read battery voltage If not check that the supply lead via ignition switch and its connections are in good condition Note Some vehicles are fitted with a pressure switch in the relay earth lead Connect a temporary Fig 69 Drive belt tension with C1 amp C2 for voltmeter testing from battery Fig 70 Checking 6RA relay STARTER SOLENOID to ignition switch to regulator Page 32 Fig 71 Checking 16RA relay lead between terminal W2 on the relay and Ammeter should now show a charge and the volt earth If voltmeter now reads battery voltage meter 6 8V the pressure switch is probably faulty Note 1 If the alternator stops charging when Cl and C2 are re connected to the relay proceed to Test b 2 If ammeter indicates a charge but voit meter reads zero proceed to Test c TEST 5 Checking 16R Relay The I6RA relay is checked a similar manner to the 6RA The various checks are shown in Fig 71 Connect ammeter in the main charging lead to the battery b The following circuit checks must be carried out a Remove connections Cl and C2 and link to before condemning the relay gether Fig 71a Connect voltmeter between Connect voltmeter between the following points WI and earth Results Run alternator at charging speed 1 500 engine i Cl and earth Fig 71b
4. The complete procedure is as follows TEST 1 Checking the Battery Terminal Voltage under Load Conditions Connect the voltmeter across the terminals as shown in Fig 17 and operate the starter switch The readings for a 12 volt system depend on the engine capacity battery size Ah and type of starter A typical figure for petrol engines is about 10 0V and for diesel engine 12V system 9 0V A low voltage reading would indicate excessive current flow in the circuit The starter should then be removed for bench testing Note If the solenoid operates intermittently during the test or the engine is cranked at a low or irregular speed there may be insufficient voltage at the solenoid operating winding terminal or the solenoid is faulty To check the switching circuit for high resis tance connect the voltmeter between the solenoid operating winding terminal and earth commutator end bracket as shown in Fig 18 When the switch contacts are closed the reading on the voltmeter should be slightly less than the reading in Test 1 A satisfactory reading indicates a negligible voltage drop in the circuit and consequently the fault may be in the solenoid If the reading is appreciably lower than in Test 1 check the switching circuit for high resistance or faulty connections Check the cable size is as recommended i e 28 0 30 mm 28 0127 In order to reduce voltage drop in the switching circuit on some vehicle applications a 4ST s
5. how ever the motor is satisfactory the fault lies in the switch or wiring on the vehicle Should the current consumption during the tests exceed 4 amps remove the wiper arms and blades and repeat test If current is still high this could indicate excessive friction in the rack or link drive mechanism Disconnect the drive from the motor and again check current consumption A high current reading now indicates a faulty motor On the rack type drive a pull Fig 93 Checking the wiper motor transmission of 6 Ibf applied to the crosshead with a spring balance should be sufficient to move the crosshead within the outer casing see Fig 93 If not the assembly must be examined for faults Note It should be remembered that where excessive friction exists overloading will result Replacing the motor will nor solve the problem In cases where removal of the arms and blades lowers the current consumption the fault is due to either a contaminated screen or faulty arms or blades 6lbf maximum Page 44 NOTES All Specifications Subject to Change Without Notice Printed In U S A
6. registers nominal battery voltage usually 12V The ammeter should then read approx 2A If the ammeter indicates a higher current the field resistance is low Fig 58 Testing the field circuit TEST 5 Checking Dynamo Leads If the correct readings are obtained on the tests at the dynamo the fault could be in the wiring between dynamo and control box To prove these cables test as follows Re connect the leads at the dynamo and dis connect D and F at the control box Connect one lead of the voltmeter to earth the other to the D lead Fig 59 and run the engine at charging speed The read ing should be the same as at D on the dynamo 1 5 3 0V No reading indicates a faulty D lead a high reading indicates a short between the D and F cables If the reading is correct leave voltmeter in position CD to earth and short F lead to D lead Volt meter needle should rise with increasing speed If the reading increases only slightly an open circuit F lead is indicated A zero reading denotes F lead shorted to earth COMPENSATED VOLTAGE CONTROL TEST 6 Open Circuit Voltage Setting Re connect D and F leads to control box Remove the A and Al leads and join the two to gether Fig 60 Connect the voltmeter between terminal D and earth and run the engine up until voltmeter settles Increase speed slightly and then regulation should
7. 3 Checking the Starter Terminal Voltage under Load Conditions Having ascertained the battery voltage the voltage across the starter is checked Fig 11 shows a voltmeter connected between the starter terminal and earth commutator end bracket When the starter operating switch is closed the difference between this reading and that taken at the battery should not exceed 0 5V If the voltage drop is excessive proceed with the following tests TEST 4 Checking the Voltage Drop on the Insulated Line For this test the voltmeter should be connected as shown in Fig 12 The voltmeter is connected between the starter terminal and the battery supply terminal When the operating switch is open the voltmeter should register battery voltage but when the operating switch is closed the voltmeter reading should be noted TEST 5 Checking the Voltage Drop across the Solenoid Contacts The solenoid contacts can be checked for voltage drop by connecting a voltmeter across the two main terminals as shown in Fig 13 When the operating switch is open the voltmeter should register battery voltage When the operating switch is closed the volt meter reading should be noted TEST 6 Checking the Voltage Drop on the Earth Line To check the voltage drop on the earth line connect the voltmeter between the battery earth terminal and the starter earth commutator end bracket as shown in Fig 14 When starter operating switch is closed the voltage re
8. ELECTROLYTE LEVEL the electrolyte must be maintained at the correct height which is normally level with the tops of the separators or the splashguard 3 TOPPING UP should be carried out when the electrolyte falis below the correct level Only distilled water or de ionised water must be added to replace electrolyte lost by evaporation 4 STATE OF CHARGE the battery must never be left in a discharged state A battery in a poor state of charge i e less than 70 should be removed and charged from an independent source at the normal recharge rate Otherwise the plates may become sulphated hardened making it difficult to accept ELECTROLYTE LEVE Page 5 a charge with the consequent early failure of the battery Ensure that the generator drive belt is adjusted correctly and that it does not rest on the bottom of the pulleys 5 INSTALLATION the battery must be securely clamped not overtight to prevent damage from vibration which may cause shedding of active material from the plates resulting in a loss of capacity or short circuit between the plates The stowage area must also be kept clean and dry Any acid spillage should be removed with house hold ammonia or baking soda and hot water otherwise the metal will be extensively damaged by corrosion The metalwork should be repainted with acid resisting paint after the corrosion has been neutralised CARE OF BATTERY LUGS Fig 4 The effect
9. SOLENOID STARTER SOLENOID TO STARTER 12 VOLT BATTERY WELL CHARGED Fig 75 Checking 3AW warning light control TEST 9 Checking 3AW Warning Light Control systems 14 15V 24V systems A hish voltage The 10AC and alternator systems normally or no reading at the AL terminal indicates faulty rectifier diode c Remove the leads from terminals E WL on the and link them together Fig 75b incorporate a 3AW charge warning light control If the charging system is operating satisfactorily but the warning light does not function correctly either by remaining on or off it indicates that the 3AW or When the ignition is switched on the warning the connecting wire is faulty lamp should be illuminated a Connect a voltmeter between the AL terminal of Note 1 If the bulb now lights the 3AW control is the alternator and earth Fig 75a probably faulty b Start and run the engine at approx 1 500 rev min 2 Should the warning light remain out the The voltmeter should read between 6 8V 12V bulb and circuit should be checked Page 35 Fig 76 Hydrometer test 15 16 17 18 20ACR SYSTEMS TEST 1 Battery Test Using a hydrometer check that the battery is at least 70 charged and in good condition see Fig 76 A battery fault can have an adverse effect on the charging system For example a sulphated battery will produce a low c
10. System voltage rev min i C1 and W2 Fig 71c System voltage To Starter Solenoid Fig 72 Checking field circuit Page 33 With ignition switched on i R and earth Fig 71d System voltage ii C2 and earth Fig 71e Approx 2 volts c Remove AL lead at alternator and connect volt meter between AL terminal and earth Fig 71f Run engine at charging speed Voltmeter should read 6 8V 12V systems or 14 15V 24V systems If meter shows zero reading replace alternator TEST 6 Checking Field Circuit Disconnect leads from the voltage regulator and link together F and terminals using an ammeter Fig 72 If 16RA is used connect terminals Cl and C2 With the ignition on the ammeter should read approx 3A Note If there is no reading connect voltmeter across alternator field terminals Close ignition if the voltmeter reads battery voltage there is a fault in the alternator field No reading indicates a wiring fault between the alternator field ter minals and the relay or regulator F terminals on positive earth check earth fly lead TEST 7 Checking Alternator Maximum Output Short out F and and connect the ammeter in the main output lead at the alternator or starter solenoid as shown in Fig 73 Run the engine at approx 3 000 rev min The ammeter reading should be Alternator Model Ammeter Reading 10AC 35A
11. TEST 7 Page 37 INTRODUCTION In order to comply with legal requirements the motor vehicle must be fitted with certain forms of lighting which must be maintained in working con dition Although the requirements may vary slightly with different types of vehicles in general the present requirements are as follows I Headlamps two minimum 2 Side rear and number plate lamps 3 Direction indicator lamps 4 Stop lamps Apart from the legal aspect efficient lighting will enable the driver to see and be seen and a driver using defective or incorrectly aligned lamps is not only a danger to himself but also to other road users t must be remembered that lights and lamp alignment are part of the M O T test on vehicles requiring a certificate BATTERY Page 38 e Q Fig 82 Checking the side y and light circuit IGNITION SWITCH LIGHTING Additional lamps may be fitted to a vehicle but they must comply with the regulations governing those particular lamps For example any additional lamps fitted to the front of a vehicle where the mounting height exceeds 24 from the ground to the centre of the lamps automatical ly become headlamps unless they are used in con ditions of fog or falling snow As such they must comply with requirements applicable to headlamps When testing lighting circuits the volt drop prin ciple will be used This will involve checking the supply voltage availa
12. battery to be charged at lower engine speeds This can be beneficial in high density traffic conditions and on modern vehicles with high electrical loads 1 110 1 130 DISCHARGED 1 230 1 250 70 CHARGED 1 270 1 290 CHARGED Page 31 In this section we shall discuss the test procedure for two types of A C system l The battery excited machine 1 0 and where the alternator field depends on the battery via a relay for its initial excitation Consequently a flat battery would result in no charge even if the vehicle is started by towing which is possible with a Diesel engine 2 The self excited machine the AC and ACR range where although some excitation is provided from the battery via the warning light this is not essential as the machine is capable of supplying its own field circuit when driven fast enough The difference between an AC and ACR system is that the former uses an external regulator whilst the ACR has its tegulator incorporated in the machine TEST 1 Battery Test Using a hydrometer check that the battery is at least 70 7 charged and in good condition see Fig 68 A battery fault can have an adverse effect on the charging system For example a sulphated battery will produce a low charge rate while a battery with a Shorted cell will produce a high charge rate TEST 2 Drive Belt Tension Allow 13 19 mm 0 5 0 75 play when moderate finger pressure is applied to the long
13. be removed and the voltage regulator setting adjusted by means of the special tool A regulator checked and found to be stable at not more than 0 5V above or below the checking limits see table must be re set to the nearest outside limit high low If the setting is more than 0 5V outside the limits the regulator can be considered faulty and should be replaced The regulator must be adjusted by means of the special tool Note Boxes under warranty should be replaced O C Ambient Voltage If Reset Temperature Checking Between to 0 25 C 14 5 15 5 14 0 14 5 14 5 32 77 F 15 5 16 0 15 5 26 40 C 14 25 15 25 13 75 14 25 14 25 78 104 F 15 25 15 75 15 25 TEST 2 Cutting in Voltage The cutting in voltage is checked as shown in Fig 65 Connect an ammeter between the B leads and the B terminal on the control box Keep the voltmeter in the same position as the previous test between ter minal D and earth Switch on headlights Start the engine and gradually increase the speed When the cut out points close the voltmeter needle will kick back This should occur within the limits 12 7 13 3V If it does not the cut out setting should be adjusted by means of the adjustment screw at the back of the cut out frame 6GC or special tool RB340 RB 340 VOLTAGE REGULATOR SETTING Fig 64 Checking the voltage regulator setting RB 340 CUTTING IN VOLTAGE Fig 65 Checking t
14. dynamo is also alternating current which has to be converted to direct current before it can be used to charge the vehicle battery In the case of the dynamo the alternating current is rectified by means of a commutator and brush gear The output of the alternator is rectified by semi conductor devices which allow electricity to flow in one direction only and so supply uni directional current to the vehicle electrical system The alternator output is controlled by a voltage regulator which is completely electronic having no vibrating contacts The use of printed circuits and Fig 68 Hydrometer test semi conductor devices make this type of regulator more reliable and more stable than the conventional type of mechanical regulator used with dynamos No cut out is required with this type of control since the semi conductor devices prevent reverse currents from flowing Also the self regulating properties of the alternator limit the output current to a safe value so that there is no need for a current regulator The latest alternators represent an important development in design as the alternator and voltage regulator are combined to form a single unit the regulator being housed within the end cover of the alternator This simplifies the charging circuit without changing the operating principles Alternator design and construction allows a wider speed range and utilisation of higher pulley ratios which in turn enables the
15. earth con nection as V4 Note the reading If the total of the readings for Tests 3 and 4 exceeds 10 of the system voltage a high resistance exists on either the insulated or earth lines or possibly both Bearing in mind that the total volt drop allowed is 10 approx 1 2 for a 12 volt system it is per misible to have all this drop on one line or the other or as a combination of both lines TEST 5 Bulb earth connection If the volt drop figure on the earth side is the higher it is probably due to a bad connection between the lamp body and earth To check connect the voltmeter BATTERY SOLENOID IGNITION SWITCH Fig 83 Checking the headlamp circuit between the bulb earth connection and a good vehicle earth V5 Any reading indicates volt drop TESTS 6 7 8 9 and 10 Checking insulated line To check volt drop on the insulated line connect one voltmeter lead to the battery insulated terminal and move the other voltmeter connection as in V6 V7 V8 V9 and VID until the faulty section is located HEADLIGHTS STOP LIGHT AND DIRECTION INDICATOR CIRCUITS To check these circuits exactly the same procedure is used as described for the side and tail circuit Refer to Figs 83 84 and 85 In the case of direction indicators one additional test is carried out together with the volt drop tests This involves removing the two leads from the 8FL flasher unit or the leads marked B and L from th
16. is obtained when the contacts are flicked open as in the previous test the secondary winding of the ignition coil is faulty However if the spark is now improved it shows that the original capacitor was not functioning satisfactorily fe TO IGNITION SWITCH Fig 29 Voltage at terminal of coil contacts closed TO IGNITION SWITCH Y i EARTH AT ENGINE FLICK CONTACTS Fig 30 Checking the secondary circuit Page 17 Fig 31 Checking the capacitor Fig 32 Checking the rotor arm insulation TEST 9 Checking the Rotor Arm Insulation Next the rotor arm is checked to ascertain whether it is punctured this would cause the spark to be earthed on the cam head However as the punctures are in visible to the naked eye the following method is adopted An H T lead is connected in the chimney of the ignition coil and the other end is held approx 3 mm 0 125 from the rotor arm electrode as shown in Fig 32 When the ignition is switched on the contacts are flicked open If there is a spark it proves that the rotor arm is earthed the cam head The rotor arm should therefore be replaced The H T spark referred to should not be confused with the faint sparking due to electrostatic charge and leakage Page 18 E 0 125 DISTRIBUTOR COVER AND H T LEADS Fig 33 The distributor cover should be thoroughly cleaned inside and outside with a sof
17. lf the battery has a capacity of 50 Ah 20 hr rate the tester should be set to 150 amps on the ammeter Observe the voltmeter during the battery discharge If the voltmeter reading is 9 6V or above the battery is considered satisfactory If the voltage falls below 9 6V the battery is suspect and should be removed for further testing TEST 3 Battery Testing Twin Cadmium Test Charge a 12 volt battery at 40 amps or at the 20 hour rate whichever is the lower for 3 minutes At the end of three minutes and with the battery still on charge Fig 9 record the overall voltage and the 5 intercell readings i e 1 and 2 2 and 3 3 and 4 4 and 5 5 and 6 using cadmium sticks Subtract the lowest intercell voltage readings from the highest CONCLUSION a If the variation is 0 15 volts or more the battery needs replacing b If the variation is less than 0 15 volts and the battery voltage is less than 15 5 for a 12 volt battery or 7 75 for a 6 volt battery the battery is satisfac tory but discharged and only in need of a fast charge c If the variation is less than 0 15 volts and the battery voltage is 15 5 or over for a 12 volt battery 7 75 for a 6 volt battery the battery is discharged and may be sulphated Page 9 INTRODUCTION The starter is a motor which converts electrical energy supplied from the battery into mechanical energy for the purpose of cranking the engine There are two basic types of starter
18. take place within the limits 16 to 16 5V If the voltmeter readings are outside the appropriate limits the voltage setting must be adjusted by turning the adjustment screw at the back of the regulator frame Turn the screw clockwise or inwards to increase the voltage and anti clockwise or outwards to reduce it If turning the adjustment screw has no effect on the voltage setting reading off the scale check for a faulty control box earth connection or n open circuit shunt winding Fig 59 Checking the dynamo leads D Page 27 OPEN CIRCUIT VOLTAGE SETTING Fig 60 Checking the open circuit voltage setting TEST 7 Cutting in Voltage Next the cutting in voltage must be checked Fig 61 Connect an ammeter between the control box A terminal and the leads which have been disconnected from the A and Al terminals The voltmeter is kept in the same position between the D terminal and earth Switch on headlights Start the engine and gradually increase the speed When the cut out points close the voltmeter needle will kick back This should occur within the limits 12 7 13 3V If it does not the cut out setting should be adjusted by means of the adjusting screw at the back of the cut out Adjust with engine stationary and repeat test Increase the engine speed The ammeter reading should increase with speed The actual reading will depend on the state of the battery charge and the electrical loa
19. the inertia type and the pre engaged type employing different methods of coupling the starter drive pinion to the engine fly wheel ring gear The inertia type used on the majority of cars and light commercials employing petrol engines When the starter is energised rapid increase of speed at the armature and screwed sleeve carrying the pinion causes the pinion to move along the sleeve due to its inertia and engage the ring gear thus rotary movement is transmitted to the engine the ratio between the starter pinion and the ring gear being approximately 10 1 When the engine fires and the flywheel accelerates to drive the pinion faster than the rotation of the armature the pinion is ejected back along the screwed sleeve and consequently disengaged from the engine The pre engaged type used on heavier petrol engines but particularly suitable on diesel engines where due to intermittent firing characteristics and cranking speed surges high compression the pinion of the normal inertia type would be ejected prematurely By the operation of a solenoid the starter pinion is engaged with the flywheel ring gear before the starter is energised after which the pinion can be retained in mesh for as long as is necessary to start the engine When the engine is firing and the pinion being driven at high speed by the flywheel the armature is protected against overspeeding by the freewheel action of a roller or plate clutch STARTER SOL
20. the output terminal of the ignition switch and the other side to the D terminal usually done at the control box D terminal as shown in Fig 63 With the ignition on and the engine stationary battery voltage is applied to one side of the warning light via the ignition switch The other side is connec t d to earth via the dynamo armature and brush gear When the engine is started and the rev min increased voltage from the dynamo D terminal rises at one side of the bulb to oppose battery voltage at the other side The warning light then fades until both voltages are equal when it is completely extinguished At almost the same instant the cut out points close 13V thus shorting out the warning light and allowing the bulb to remain out A warning light that glows faintly under normal running conditions can be due to any of the following faults i 1 Internal high resistance in the ignition switch 2 Dirty control box cut out contacts 3 A slipping fan belt if slipping badly enough WARNING LIGHT Fig 63 Ignition warning light circuit CURRENT VOLTAGE CONTROL TEST 1 Voltage Regulator Setting Remove the leads from the B terminal if more than one join them together Connect a voltmeter between the D terminal and earth Fig 64 and run the generator up to a stable unning speed normally about 3 000 rev min If the voltmeter readings are outside the appropriate limits the cover must
21. usually to a low SMINVIT CLAMP TYPE CONSTANT CURRENT CHARGING AMMETER Fig 6 Constant voltage charging voltage motor generator set The number of batteries that can be charged by one generator is limited by the rated current output of the generator and the total charging current required for all the batteries must not exceed this output The supply voltage can again be regulated by a rheostat and if necessary a rheostat or resistance can be included in the supply line to an individual battery where a lower charging rate is required TEST 1 Battery Testing Hydrometer Testing should commence at the source of supply the battery itself If the battery is discharged or un serviceable the readings in the other tests will be affected NO VOLT SUPPLY CONSTANT VOLTAGE D C SUPPLY CONSTANT VOLTAGE CHARGING There is a relationship between the state of battery charge and the strength of the electrolyte As the battery becomes discharged the specific gravity S G of the electrolyte becomes lower The S G of the electrolyte is measured by means of a hydrometer This instrument consists of a glass tube with a rubber bulb fitted on one end Inside the tube there is a float which is calibrated from 1 130 to 1 300 When the end of the hydrometer is inserted in the battery cell as shown in Fig 7 and the rubber bulb is pressed and then released a small quantity of the electrolyte is
22. 5 Checking for H T sparking TO IGNITION SWITCH Fig 26 Voltage at terminal of coil contacts closed TO SwITCK Fig 27 Voltage at terminal of coil contacts open Fig 28 Distributor earth TEST 5 Distributor Earth If the last test has shown that the distributor is short circuited to earth the following points in the L T line should be checked see Fig 28 The lead between the ignition coil terminal and the distributor L T terminal b The flexible lead connecting the distributor L T terminal to the moving contact terminal post c The flexible lead connecting the contact breaker terminal post to the capacitor d Also check that the tags on the ends of the capacitor and flexible leads at the L T terminal post are under the shoulder of the nylon bush and not under the securing nut e Finally check that the capacitor is not earthed This is achieved by disconnecting the capacitor from its mounting TEST 6 Voltage at Terminal of Coil Contacts Closed When all connections are re made the voltmeter is left connected as in the previous test i e between the coil terminal and a good earth Fig 29 The contact points are closed by rotating the engine When the ignition is switched on a zero reading should be obtained If the voltmeter registers a voltage it is due to one of the following faults 1 Dirty or oily co
23. Catalog No XIA116 Lucas iagnosis Fault D Serv Manual ICe Fault Diagnosis Service Manual Information contained herein has been carefully researched reliable sources While all information is believed to be complete and accurate we cannot accept responsibility for any error or omission We reserve the right to make any necessary changes at any time without notice Should an error or omission be found please report it immediately to the Lucas Aftermarket Operations Marketing Department Introduction Fault diagnosis is the method of locating faults while the electrical equipment is still in situ In the interests of efficiency and economy the diagnosis must be accurate and must be carried out in the shortest possible time using the minimum amount of equipment lt is the aim of this book to present a logical sequence of tests that may be carried out on the various sections of the equipment in order to achieve this objective The majority of procedures involve circuit testing and the principle used will be that of checking for voltage drop where a voltmeter is connected in parallel with the particular circuit to be tested As voltage drop exists only when current is flowing and varies according to the amount of current it is essential that the circuit is checked under load i e whilst passing its normal current In certain instances this current will be measured using a test ammeter The acceptable volt drop figure fo
24. ENOID Fig 10 Battery terminal voltage under load Page 10 STARTER SOLENOID Fig 11 Starter terminal voltage under load TEST 1 Battery Test Using a hydrometer check that the battery is at least 70 charged The full battery test procedure is outlined in Section 1 Note A battery in poor condition will cause difficult starting CHECKING THE STARTER SYSTEM INERTIA DRIVES If the previous test has proved that the battery is satisfactory a moving coil voltmeter 0 40V range should be used to determine whether there is excessive voltage drop in the circuit Note During the voltmeter checks the starter should crank the engine without starting it Petrol engines The low tension circuit of the ignition coil should be disconnected between the coil and distributor Diese engines Operate engine stop so that engine will not start TEST 2 Checking the Battery Terminal Voltage under Load Conditions This check enables the working voltage at the battery to be verified Fig 10 shows a voltmeter connected between the positive and negative battery terminals The reading is noted when the starter switch is operated The readings for a 12 volt system depends on the engine capacity battery size Ah and type of starter A typical figure for petrol engines is about 10 0 volts Proceed to Test 3 A low voltage reading would indicate excessive current in the circuit The starter should be removed for bench testing TEST
25. H T carbon brush must be free to move in its holder If the distributor cover electrodes are badly eroded or tracking has occurred a new cover should be fitted Carry out test for sparking using vehicle main H T lead instead of test lead if no spark lead is faulty ignition Switch Fig 48 Voltage at coil terminal open circult Page 24 solenoid inj Crank Engine Fig 51 Checking the rotor arm insulation ELECTRODE Fig 52 Checking the distributor cover and H T cables If spark occurs re fit distributor cap and all leads Engine should now fire Misfiring on individual cylinders could be due to a fauity H T lead to that particular cylinder or spark plugs IGNITION TIMING After checking the ignition system ensure the ignition timing is in accordance with the manufacturers recommendations Two suitable methods are shown a Static Ignition Timing b Stroboscopic Timing STATIC IGNITION TIMING Rotate the engine until No 1 piston is just before T D C on the compression stroke see Fig 53 exact position as specified by engine manufacturer At this point the rotor arm should be pointing to the distributor cap segment connected to No 1 spark plug The contact breaker points should be just at the point of opening in the direction of rotation This can be verified by connecting a voltmeter between the distributor L T terminal and a good earth At the precise moment the contact
26. OTORS Wiper test procedure Page s 2 10 14 10 10 11 12 15 25 16 19 19 21 22 24 25 25 26 30 26 26 27 27 27 28 29 29 30 37 32 32 35 36 37 36 38 41 39 39 39 41 42 44 42 3 INTRODUCTION The lead acid battery 15 a device used to convert and store electrical energy in a chemical form and as the name implies the basic active materials are lead and sulphuric acid The purpose of the battery on the vehicle is primarily to provide current for the operation of the starter but it also supplies other equipment that may be used whilst the vehicle is stationary e g radio parking lights etc During the course of normal running the battery is recharged by the vehicle charging system and provided the vehicle does enough running time will have stored energy ready for the next start operation Note A vehicle standing idle will mor maintain a charged battery As a battery fault can have adverse effects on the operation of the various systems particularly the starting and charging system some knowledge of battery testing is an essential part of fault diagnosis CLEAN AND DRY Ed ur Ad SECURELY B CLAMPED CLEAN Fig 3 Batteries in service BATTERIES BATTERIES IN SERVICE Fig 3 l CLEAN AND DRY the battery particularly the top must be kept clean and dry Water spillage etc during topping up must be immediately wiped away 2
27. ading should be practically zero STARTER SOLENOID Fig 12 Voltage drop on the insulated line TO STARTER FEED FROM BATTERY Fig 13 Voltage drop across the solenoid contacts STARTER SOLENOID Fig 14 Voltage drop on the earth line EARTH CONNECTION Fig 15 Checking the earth connections TEST 7 Checking Earth Connections Connect the voltmeter between the chassis of the vehicle and the battery earth terminal Fig 15 Operate the starter Once again note the reading TEST 8 Checking Bonding Strap Fig 16 As most vehicle engines are rubber mounted the bonding strap must make a good electrical connection between the engine block and the chassis The units mounted on the engine block i e distributor dynamo and starter must have an efficient earth connection in order to function correctly If the bonding strap is incorrectly fitted or frayed it will have a serious effect on the performance of the starter and may even immobilise the vehicle Note The total voltage drop on the starter installation must not exceed 0 5V Fig 16 Checking the bonding strap Page il Fig 17 Battery terminal voltage under load CHECKING THE STARTER SYSTEM PRE ENGAGED DRIVES The procedure for checking for excessive voltage drop in the pre engaged starter circuit is similar to that used for inertia drive starter systems but in addition the voltage available at the solenoid feed terminal must be checked
28. and the voltmeter should dissipates some of the heat produced in the circuit register approx 6V for a 12 volt ballasted system TEST 1 Voltage at Terminal of Coil If the correct voltage is indicated the supply from the Ballasted System Contacts Closed battery to the ignition coil is satisfactory Next tem porarily earth the coil negative terminal and crank the engine by the starter any increasein the voltage indicates a satisfactory circuit A slight decrease indicates a faulty solenoid switch or lead from the solenoid switch Remove temporary earth connection If no readings are obtained proceed with the Tests 2 and 3 If correct readings or battery volts are ob tained proceed to Test 4 TEST 2 Voltage at Side of Ballast Resistor With the contacts closed connect the voltmeter V2 between the feed side of the ballast resistor and a good earth Fig 38 On applications with resistive supply cable connect the voltmeter between the ignition switch end of the cable and a good earth If battery voltage is registered proceed to Test 3 But if no voltage is indicated check back along supply cable TEST 3 Voltage at Coil Side of Ballast Resistor Connect the voltmeter V3 between the coil side of the ballast resistor and a good earth Fig 38 The ignition is switched on No reading indicates a faulty ballast resistor TEST 4 Voltage at Terminal of Coil Contacts Open With contacts open connect t
29. avity If however the battery should become fully discharged it should not be left on the vehicle in the hope that it will become fully recharged by the vehicle s charging system Unless the battery is charged by an external source it will probably never become more than half charged and even though it appears to be working satisfactorily the plates will harden and the life of the battery will be considerably shortened Generally speaking recharging presents no problems if the recharging rates quoted on the instruction labels are adhered to The normal charge rate is approxi mately one tenth of the A H capacity of the battery at the 10 hour rate or 20 hour rate CHARGING METHODS Either the constant current method which we advocated for initial charging or the constant voltage method may be employed for recharging In either case a DIRECT CURRENT supply must be used The connections to be made differ with the method and can be seen fromthe diagram You will see that using the constant current method Fig 5 the batteries are in series Thus a limit is set to the number of batteries that may be charged in series since the voltage of the batteries when fully charged must not exceed the supply voltage It is found in practice that the most suitable arrangement is ten 6 volt batteries or five 12 volt batteries when charging from a 110 volt supply With the constant voltage system Fig 6 the batteries are connected in parallel
30. ble under load at the battery then the voltage available at the actual lamp involved Where the difference in voltage exceeds the permitted limits the voltmeter will be connected in parallel with both the supply and return sides of the circuit to deter mine where the fault exists The exact procedure will be stated in this section In the case of direction indicator circuits it will be necessary to use an ammeter in addition to the volt meter as the operation of the flasher unit is depend ent on current consumption bM TAIL LAMPS OC 2 0 SIDE LAMPS J LiGHTING SWITCH TO DIP SWITCH SIDE AND TAIL LIGHT CIRCUIT ALL TESTS WITH SIDE AND TAIL LIGHTS SWITCHED ON Refer to Fig 82 for voltmeter positions TEST 1 Voltage at the Battery under Load Connect voltmeter V1 across the battery terminals and note the reading TEST 2 Voltage at bulb connections Connect the voltmeter across the bulb connections as V2 Note the reading The difference in reading volt drop should not exceed 10 of the system volt age If the volt drop is excessive proceed to Test 3 insulated line TEST 3 Voltage drop on insulated line Connect one side of voltmeter to the battery in sulated terminal and the other side to the bulb in sulated connection as V3 Note the reading TEST 4 Voltage drop on earth line Connect one side of the voltmeter to the battery earth terminal and the other side to the bulb
31. d STARTER BATTERY SOLENOIDO Fig 62 Voltage drop on the supply line Page 28 CUTTING IN VOLTAGE Fig 61 Checking the cutting in voltage Gradually reduce the engine speed The ammeter needle should fall until it indicates a discharge or reverse current of 3 5 amps The ammeter needle should return to zero when the cut out points open Replace all control box leads ensuring correct con nections TEST 8 Checking Voltage Drop on Supply Line Remove the D lead from the dynamo terminal and connect the ammeter into the circuit see Fig 62 Connect the voltmeter between the dynamo D lead removed and the battery supply terminalat the starter solenoid Start and run the engine at charging speed until the ammeter reads 10A At this point the voltmeter reading should not exceed 0 75V A higher reading than 0 75V denotes a high resist ance in the insulated circuit IGNITION WARNING LIGHT The Ignition Warning Light to use its more popular name has two basic functions Primarily to indicate that the ignition is switched on and secondly when the engine is started and the rev min increased it should fade and go out This indicates that the dynamo voltage has risen sufficiently to close the cut out switch between dynamo and battery Note The fact that the light goes out does necessarily mean that the charging system is functioning correctly One side of the bulb is connected to
32. drawn into the tube The position of the float is determined by the specific gravity of the electro lyte When the specific gravity is high the float main tains a high position inside the tube and if the specific gravity is low the float sinks to a lower position Page 7 1 110 1 130 DISCHARGED 1 230 1 250 1702 CHARGED 1 270 1 290 CHARGED Fig 7 Hydrometer test _ Fig 9 Twin cadmium test Page 8 From the specific gravity S G readings a fairly accurate indication of the battery state of charge can be obtained Specific Gravity Readings State Climates Climates of Charge normally below normally above 25 C 77 F 25 C 77 F 1 210 1 230 1 170 1 190 1 050 1 070 1 270 1 290 1 230 1 250 1 110 1 130 Fully charged 70 charged Discharged Note The hydrometer readings should not be taken if the battery has only just been topped up It should be charged for to 2 hours before taking any readings TEST 2 Battery Testing Heavy Discharge Test This test should be carried out as a further check of the battery condition A heavy discharge tester should be applied to the battery terminals as shown in Fig 8 The test ensures that the battery is capable of supplying the heavy currents required by the starter at the moment of starting the engine The tester should be set to discharge the battery at three times the ampere hour capacity 20 hr rate for 15 seconds Example
33. e FL5 and connecting an ammeter in series with these leads as shown in Fig 85 With the indicator switch in either the right or left hand position the indicator lamps on one side should light and the current registered on the ammeter should be that of the flasher unit rating E g 3 6 amps or 4 3 amps or 4 8 amps Should the current consumption not match up to that specified on the unit then the rate of flash will be incorrect This is caused by one of the following 1 The wrong flasher unit has been fitted 2 Bulbs of incorrect wattage have been fitted 3 One bulb is faulty this can be checked visually 4 A high resistance exists in the circuit This should be located using the volt drop test procedure Note When testing indicator lamp circuits do nor make a direct earth connection to any of the indicator lamp insulated connections i e bulb contacts DIP SWITCH LIGHTING SWITCH Page 39 BATTERY SOLENOID STOP LAMPS STOP LAMP SWITCH IGNITION SWITCH Fig 84 Checking the stop lamp circuit SWITCH FLASHER UNIT Fig 85 Checking the direction indicator circuit Page 40 HEADLAMP ALIGNMENT As previously stated the headlamps can only be fully efficient when correctly aligned The Lucas Beam Tester Mk III as shown in Fig 86 is an instrument designed specifically for the accurate checking and alignment of all types of vehicle head lamps In the absence of a beamtester a
34. em is to provide place extra demand on the system sufficient voltage at the spark plugs to ignite the petrol Ignition systems can be produced to comply with air mixture in the cylinders as each piston approaches these additional demands For example ballasted the correct firing position i e a few degrees before systems to facilitate easier cold starting or electronic top dead centre on compression stroke The exact systems to provide high speed operation on multi number of degrees varies with different engines and will cylinder engines be specified by the engine manufacturers The systems dealt with in this section are The amount of voltage needed will also vary with a a Standard coil ignition number of factors such as engine temperature com b Ballasted ignition easy start pression ratio spark plug gap c OPUS Oscillating pick up system fully electron Although the standard ignition system will quite ic no contacts adequately meet the requirements of a six cylinder Fig 23 shows a typical coil ignition circuit Cm lt gt IGNITION SWITCH AMMETER lt a SOLENOID id IGNITION LX SDN TS DOS Fig 23 Typical coil ignition circuit Page 15 7 Ignition Switch On Ammeter Lighting Switch On Fig 24 Battery rapid check Warning Light STANDARD COIL IGNITION SYSTEM TEST 1 Battery Rapid Check Fig 24 When dealing with
35. engine RB 340 Page 30 Still with the headlights on start and run engine at above charging speed check ammeter reading If in correct to specifications quoted replace box Fig 66 Checking the current regulator setting TEST 4 Checking Voltage Drop on Supply Line Remove the D lead from the dynamo terminal and connect the ammeter into the circuit see Fig 67 Connect the voltmeter between the dynamo D lead and the battery supply terminal at the starter solenoid Start and run the engine at charging speed until the ammeter reads 104 At this point the voltmeter read ing should not exceed 0 75V A higher reading than 0 75V indicates a high resist ance in the insulated line CONCLUSION Having obtained an idea of the various forms of Benerator control units and their working it may be desirable to add a note of caution The successful servicing of these important com ponents depends on making adjustments which are stable and permanent Only a limited amount of work can be successfully executed in the general garage If for example a control unit will not respond to the adjustments outlined it should be replaced STARTER SOLENOID BATTERY INTRODUCTION The alternator produces alternating current which is converted to direct current before being connected to the vehicle electrical system In this respect the alternator and dynamo are similar since the current generated in the armature windings of the
36. er solenoid contacts must be checked Proceed to Test 4 TEST 4 Checking the Voltage Drop across the Solenoid Contacts To check the voltage drop across the solenoid con tacts connect the voltmeter across the two main solenoid terminals as shown in Fig 21 When the operating switch is open the voltmeter should register battery voltage When the operating switch is closed the voltmeter reading should fall to a fractional value A zero or fractional reading on the voltmeter indicates that the high resistance deduced in Test 3 must be due either to high resistance starter cables or soldered connections A high reading similar to that in Test 3 indicates faulty solenoid contacts Fig 21 Voltage drop across the solenoid contacts TEST 5 Checking the Voltage Drop on the Note 1 Check earth connections and bonding strap Earth Line as described in the Inertia Starter section Finally check the voltage drop on the earth line Tests 7 and 8 Connect the voltmeter between the battery earth ter 2 The total voltage drop in the starting circuit minal and the starter earth commutator end bracket i e insulated line and earth line must not as shown in Fig 22 Note readings exceed 0 5V 77 CHASSIS Fig 22 Voltage drop on the earth line Page 14 COIL IGNITION INTRODUCTION engine up to approx 8 000 rev min any increase in speed requirements or in the number of cylinders will The function of the ignition syst
37. esistor normally comprises a coil of resistive wire housed in a porcelain block with electrical connections by means of Lucar connectors _ The ballast resistor is clamped to its fixing often an ignition coil mounting bolt by a bracket surrounding the porcelain block Note The resistor may take the form of a resistive cable on some applications The cold starting performance is improved by permitting the ignition coil to operate at a voltage slightly above its normal operating voltage Slight overloading is not detrimental to the coil as it occurs only while the engine is being cranked 0 015 GAUGE Fig 34 Checking the contact breaker assembly and gap setting Fig 35 Contact breaker adjustment for 35D distributors Page 19 IGNITION SWITCH AMMETER BALLAST RESISTOR BATTERY 4 SSR ees S by pe d AAAA CII Can CON ON Fig 36 Typical ballasted ignition system The primary winding of an ignition coil used with a Connect the voltmeter 1 between the ter ballast resistor has a lower inductance value which minal of the coil and a good earth as shown in Fig permits a more rapid build up of the magnetic field as 37 The contacts should be closed during the test to the contact points close There is also less heating enable current to flow through the primary winding effect inside the coil as the ballast resistor itself Switch on the ignition
38. est run of belt See Fig 69 The alternator will not charge the battery if the drive belt is too slack On the other hand an excessively tight belt may damage the bearings If the belt is worn or oily it should be replaced with a premium grade type TEST 3 Connections Ensure that all leads are in position TEST 4 Checking 6RA Relay The purpose of the 6RA relay is to de energise the alternator field winding when the engine is stationary The relay is connected to the ignition switch so that it operates only when the ignition is switched on The rotor field is completed by contacts Cl and C2 The alternator will not charge the battery if the relay contacts fail to close Ld 13 19mm Be 72 34 a With the engine stationary disconnect the battery earth cable and connect an ammeter in the alterna tor main output lead as shown in Fig 70 b Remove the cables from terminals Cl and C2 at the relay and link together Re connect the battery earth cable switch on the ignition and run the engine at 1 500 rev min c If the ammeter now shows a charge the previous failure was due to the relay or its associated wiring connections etc d Connect voltmeter across WI and W2 The voltmeter should read battery voltage if the relay has a good earth and supply If no reading pro ceed to e e Check relay earth connection by connecting the voltmeter between
39. f the test plug leads as shown in the following tests it will be possible to determine a That the motor is operating correctly b The current consumption of the motor 2 4 amps ALL TESTS WITH SCREEN WET ARMATURE NORMAL SPEED 14W 15W 16W WIPERS 12V SUPPLY Fig 89 Test 1 14W 15W and 16W wipers Connections Batt of motor All types Result Motor runs at normal speed Do not disconnect battery supply from plug while the wiper blades are in the parked position TEST 2 Fig 90 Yellow 2 speed motors only Self switching types only TEST 4 Fig 92 White Self parking types only ARMATURE HIGH SPEED 14 W 15W 16W WIPERS COLOUR CODE R RED YELLOW U BLUE LWIWHITE 12V SUPPLY Fig 90 Test 2 14W 15W and 16W wipers POSITION amp STOP Motor runs at high speed Motor should run to park position then stop Sa cee er Motor should run to extended park position then stop 14W amp 15W WIPERS Fig 91 Test 3 RTRED BLUE ___ 12V SUPPLY 14W and 15W wipers ARMATURE 16W WIPER Fig 92 Test 4 16W wipers PARK POSITION amp STOP COLOUR CODE IR RED 7 BLUE WHITE 12V SUPPLY If the motor fails to function in any one or more of the previous tests a faulty motor is indicated If
40. fully electronic system where the distributor cam and contact breaker assembly have been replaced by a pick up module and rotating drum carrying a number of ferrite rods one for each engine cylinder As each rod passes in front of the module a small voltage signal is generated by the module winding this signal is then transmitted to the amplifier The transistorised circuits in the amplifier unit will instantly switch off the current in the ignition coil primary winding thereby producing an induced coil secondary voltage i e the spark The ignition coil used is a special low inductance type designed for high speed operation and as such is particularly suitable for 8 and 12 cylinder engines As no contacts are used the problem of contact breaker bounce at high speed is non existent OPUS IGNITION TEST PROCEDURE TEST 1 Battery Rapid Check Fig 43 Switch on the headlights and ignition and operate the starter If the engine is turned over at a reasonable speed and the lights remain fairly bright they will dim slightly we can assume that the battery will supply sufficient current for us to be able to carry out the test procedure Should the lights dim excessively and the starter appear sluggish then the complete test procedure must be applied to the battery as in the battery section of this book TEST 2 Check for Sparking Connect a test H T lead into the coil chimney re move vehicle H T lead and hold the free e
41. harge rate whereas a battery with a shorted cell will produce a high charge rate TEST 2 Drive Belt Tension Allow 13 19 mm 0 5 0 75 play when moderate finger pressure is applied to the longest run of the belt see Fig 77 The alternator will not charge the battery if the drive belt is too slack On the other hand an excessively tight belt may damage the bearings If the belt is worn or oily it should be replaced with a premium grade type TEST 3 Connections Ensure that all leads are in position 1 110 1 130 DISCHARGED 1 230 1 250 707 CHARGED 1 270 1 290 TEST 4 Cable Continuity a Remove all the connections from the alternator terminals b Switch on the ignition Fig 77 Drive belt tension Fig 78 Cable continuity Page 36 Starter Solenoid gt Ignition 1 0 switch c Connect the voltmeter between a good earth and each of the disconnected leads in turn Fig 78 The voltmeter should indicate battery voltage Note 1 A zero reading indicates open circuit leads or faulty bulb if IND lead 2 Where the additional earth terminal is used on the alternator the voltmeter reading for that connection will be zero 4 On replacing the connections failure of the warning light indicates a faulty alternator field circuit or regulator If the warning light is illuminated proceed to Test 5 TEST 5 Checking Alternator Maximum Output The alterna
42. he cutting in voltage Page 29 Increase the engine speed and the reading on the ammeter should increase with speed dependent on state of battery charge and electrical load Gradually reduce the engine speed The ammeter needle should fall until it indicates a discharge or reverse current of 3 10 amps The ammeter needle should return to zero when the cut out points open TEST 3 Current Regulator Setting Fig 66 For the purpose of this test the dynamo must produce its safe maximum output regardle s of the state of charge of the battery therefore the voltage regulator must be made inoperative This is achieved by connecting a crocodile clip across the voltage regulator contacts Switch off all lights from previous test With the ammeter still in position connected in series with B lead start the engine and increase the rev min to just above charging speed The meter read ing should correspond to the figure shown in the table for a given dynamo Associated Nominal Setting dynamo 1 amp C40 1 44 dia fan 19A C40 1 5 dia fan 22A C40A 10 5 C40L 25A C42 30A C40T except Part No 22A 22762 C40T Part No 22762 18A Method of adjustment is similar to voltage regulator and cut out In the case of boxes under warranty where the cover should not be removed the following alternative methods of checking may be used Switch on headlights and leave on for 5 minutes be fore starting
43. he voltmeter between the coil ve terminal and earth as V4 in Fig 39 With ignition on voltmeter should read battery voltage No reading indicates open circuit coil primary winding or short circuit on the lead from the coil to distributor Fig 37 Voltage at terminal of coil contacts closed or within the distributor To obtain a good H T spark it is necessary to have a good voltage supply to the coil TO IGNITION SWITCH SOLENOID SUENO DISTRIBUTOR Page 20 TO DISTRIBUTOR Fig 38 Voltage at ballast resistor Repeat test with coil ve lead disconnected if reading now appears fault is on distributor or lead No reading faulty coil TEST 5 Distributor Earth If the last test has shown that the distributor is short circuited to earth the following points in the L T line should be checked see Fig 40 A The lead between the ignition coil ve terminal and the distributor L T terminal B The flexible lead connecting the distributor L T terminal to the moving contact terminal post C The flexible lead connecting the contact breaker terminal post to the capacitor D Also check that the tags on the end of the capaci tor and flexible leads at the L T terminal post are under the shoulder of the nylon bush and not under the securing nut E Finally check that the capacitor is not earthed This is achieved by disconnecting the capacitor from its mounting
44. hould read 0 2V If reading is battery voltage the amplifier is faulty and should be replaced together with pick up module If reading is above 2 volts but below battery voltage check volt drop on amplifier earth connection by con necting voltmeter between amplifier housing and a good earth With ignition on voltmeter should show 0 5V maximum If higher amplifier has a bad earth connection TEST 8 Amplifier Switching Re connect amplifier distributor socket Connect voltmeter between a good earth and coil terminal Fig 50 With test H T lead connected in coil chimney hold free end 6 mm 0 25 from the engine block Switch on ignition and crank engine voltmeter reading should be 3 4V fluctuating with regular sparking from H T lead A fluctuating voltmeter reading with no H T spark indicates a faulty coil secondary winding replace the coil If voltmeter stays at low reading below 2V with no spark amplifier is faulty should be replaced TEST 9 Rotor Arm Insulation Hold free end of test H T lead approx 3 mm 0 125 from centre of rotor arm electrode see Fig 51 Switch ignition on crank engine No spark should occur If a good spark occurs replace the rotor arm A good spark should not be confused with the very faint sparking that may be seen due to electrostatic charge and leakage TEST 10 Distributor Cover and H T Cables Fig 52 The distributor cover should be clean and dry The
45. ing the hexagon shaped stud which protrudes through the distributor body It is adjusted to give the correct dwell angle contact closed period see Fig 35 Adjustment should be carried out using a dwell meter with the engine running The dwell angle should be set within the limits specified by the manufacturer The hexagon shaped stud is screwed anti clockwise to in crease the dwell angle close the contact point gap and clockwise to decrease the dwell angle open the contact gap Note Static and stroboscopic timing are described at the end of the chapter BALLASTED IGNITION SYSTEM Ballasted ignition systems Fig 36 are used to im prove engine starting especially in very cold con ditions and also to provide maximum spark efficiency at high engine speeds Battery voltage is at its lowest when the engine is being cranked This drain on the battery causes the terminal voltage to fall well below its normal value Consequently during starting the H T spark is ob tained from an ignition coil which is operating from a reduced voltage In these conditions the ignition performance is usually satisfactory but in extremely cold conditions it is preferable to use a system in which the voltage applied to an appropriate coil remains constant A ballast resistor is connected in series with the ignition coil primary winding and the circuit is arranged to short out the resistor when the starting motor is operating The ballast r
46. le manufacturer s information Fig 54 Stroboscopic timing Page 25 DYNAMOS AND CONTROL BOXES INTRODUCTION The D C charging system is designed to maintain the battery in a reasonable state of charge under average running conditions This means that the dynamo output must be sufficient to supply the normal continuous vehicle electrical load plus the little extra required to keep the battery charged The inherent design of the dynamo is such that it must always be under some form of control both to protect the machine against overload and to protect the battery against overcharge A control box therefore is designed to operate with a specific type of dynamo on a given application For many years the Compensated Voltage Control 2 bobbin system has been employed and in fact is still used on certain present day production vehicles However with the increase in electrical equipment fitted to the modern vehicle it became necessary to utilise a system better suited to present day require ments This brought about the Current Voltage Control 3 bobbin system The main advantage of this system is that it allows maximum safe dynamo out put for a longer period of time when the battery is in a discharged condition Dynamos or control boxes may be replaced as individual units provided two rules are strictly ob served 1 That the correct replacement unit is fitted 2 That after fitting the test pr
47. n alternative but less accurate method of checking the alignment is as follows see Fig 87 Position the vehicle on a piece of level ground 25 ft from the wall or door to be used as a screen 25 ft is required in order to obtain a suitable beam pattern The vehicle must as far as possible be at right angles to the wall or door Crosses are marked on the wall corresponding to the same centres as the headlamps i e same distance apart and from the ground These marks are then used as a guide line for the correct alignment Fig 86 Lucas Beam Tester Mk lil Centre Line Area Of Concentrated Of Vehicle Distance Between Light Lamp Centres Height Of Lamp Centres From Ground A Front Of Vehicle To Be Square With Screen B Vehicle To Be Loaded And Standing On Level Ground C Recommended Distance For Setting Is At Least 251 D For Ease Of Setting One Headiamp Should Be Covered Fig 87 Headlamp alignment without beam tester Page 41 INTRODUCTION The modern wiper motor is a permanent magnet type incorporating two ceramic magnets housed in a cylindrical steel yoke This type of arrangement pro duces a higher torque output than a normal wire wound field system and consequently wiper arms having in creased spring pressure can be used Permanent magnet wipers are produced in either single or two speed form The high speed require ments are provided by a second positi
48. nd approx 6 mm 0 25 from the engine block as shown in Fig 44 With the ignition on crank the engine Regular sparking should occur If no sparking occurs proceed with tests in sequence If sparking occurs carry out Test 3a only then proceed to Tests 9 and 10 Page 22 Ammeter Lighting Switch On Warning Light Fig 43 Battery rapid check Fig 44 Checking for sparking 0 9 ohm 210 OHMMETER 2 5 10 0 020 0 022 AIR GAP CHECK Fig 45 Checking the distributor pick up module Test 3 Distributor Pick up Module a Module air gap Rotate the engine so that the ferrite rod marked No 1 cylinder on Jaguar or the rod immediately under the rotor electrode on Aston Martin is in line with the pick up module see Fig 45 The gap between module and timing rotor should be a parallel 0 50 0 55 mm 0 020 0 022 If in correct adjust by slackening module fixing screws b Disconnect the distributor to amplifier plug and on the distributor side use an ohmmeter to check the resistance values between the centre and each outer terminal The readings should be Centre terminal to outer terminal with red cable 2 5 ohms 10 centre terminal to outer terminal with black cable 0 9 ohm 10 Leave plug dis connected TEST 4 Check Ballast Resistor 9BR Withdraw socket at amplifier side of ballast resistor Connect the voltmeter between a good earth and each terminal of the ballast
49. ntacts 2 Faulty earth connection i e between the distributor shank and the engine block or the flexible lead from the contact plate to earth Contacts not closing properly 4 A high resistance in circuit from the coil to the C B on the distributor 5 Broken flexible lead between the distributor L T terminal and the contact breaker terminal post 6 Open circuit coil to distributor lead Uu TEST 7 Checking the Secondary Circuit The secondary circuit is checked to ensure that sufficient voltage is induced in the secondary winding to produce a high voltage spark One end of a known good H T lead is connected in the H T outlet of the ignition coil The other end is held approximately 6 mm 0 25 from a clean area of the engine block Fig 30 With the distributor con tacts closed the ignition is switched on The contacts are then flicked open and if a good strong spark is obtained across the gap for each flick it proves that the ignition coil and capacitor are serviceable If no spark occurs until the 6 mm 0 25 gap is reduced this indicates either a faulty capacitor or weak secondary output proceed to next test TEST 8 Checking the Capacitor The capacitor is checked by substitution The original capacitor is disconnected and a test capacitor known to be serviceable is connected between the distributor L T terminal and earth as shown in Fig 31 Switch on the ignition If an unsatisfactory spark
50. ocedure is carried out on both units to ensure that the complete system is operating efficiently Page 26 TEST 1 Battery Test Using a hydrometer check that the battery is at least 70 charged and in good condition see Fig 55 A battery fault can have an adverse effect on the charging system For example a sulphated battery will produce low charge rate whereas a battery with a shorted cell will produce high charge rate CHECKING DYNAMO TEST 2 Drive Belt Tension Allow 13 19 mm 0 5 0 75 play when moderate finger pressure is applied to the longest run of the belt Fig 56 The dynamo will not charge the battery if the drive belt is too slack On the other hand an excessively tight belt will damage the bearings If the belt is worn or oily it should be replaced 1 110 1 130 DISCHARGED 1 230 1 250 702 CHARGED 1 270 1 290 CHARGED Fig 55 Hydrometer test Fig 56 Drive belt tension TEST 3 Testing the Armature Circuit Disconnect the leads at the dynamo and connect the voltmeter between a good earth and the dynamo D terminal Fig 57 Start the engine and slowly increase the speed to approx 1 500 rev min The voltmeter should register 1 5 3 0V TEST 4 Testing the Field Circuit The voitmeter is kept in the same position as for the previous test between terminal D and earth and an ammeter is connected between D and F Fig 58 The engine speed is increased slowly until the voltmeter
51. of acid corrosion is far more serious than is generally realised For example excessive corrosion of the battery lugs will lead to sluggish operation of the starter This is due to voltage drop at the battery terminals when the high starter current is flowing The lead die cast lug is designed to reduce the possibility of corrosion to a minimum and is fitted almost exclusively to British cars today The S M M T lug clamp type is used mainly on commercial and passenger vehicles In both cases the lug should be cleared of oxidation and the lug and battery post smeared with petroleum jelly as an added precaution against corrosion When fitting the die cast lug ensure that it is in full contact with the terminal post by pressing it down firmly and securing it in position with the self tapping screw Do not use the screw to pull thelug down on to the terminal post Never use force when removing lugs If as a result of corrosion a lug cannot be removed easily soak a DIE CAST HELMET TYPE Fig 4 Types of battery lugs Page 6 cloth in hot water and apply it to the corroded lug After freeing the lug remove all traces of corrosion CORRECT CHARGING The importance of correct charging cannot be over emphasised as far as the life of the battery is con cerned The battery should not be allowed to stand in a low state of charge especially in the winter when the electro lyte could freeze due to its low specific gr
52. olenoid is incorporated in the circuit as shown in Fig 18a Page 12 TO BATTERY Fig 18A Solenoid switching circuit incorporating additional solenoid 4ST TEST 2 Checking the Starter Terminal Voltage under Load Conditions Having ascertained the battery voltage under load the voltage across the starter is checked Fig 19 shows a voltmeter connected between the starter input terminal and earth commutator end bracket When the operating switch is closed the difference between this reading and that taken at the battery should not exceed 0 5V If the reading is within this limit the starter circuit is satisfactory If there is a low reading across the starter but the voltage at the battery is satisfactory it indicates a high resistance in the starter circuit Fig 20 Voltage drop on the insulated line TEST 3 Checking the Voltage Drop on the Insulated Line The voltage drop on the insulated line is then checked Fig 20 shows the voltmeter connected between the starter input terminal and the battery insulated terminal When the operating switch is open the voltmeter should register battery voltage When the operating switch is closed the voltmeter reading should be practically zero A high voltage reading indicates a high resistance in the insulated line All insulated connections at the battery solenoid and starter should be checked Page 13 If all connections are in order the start
53. r most circuits is 10 of system voltage 1 2 volts on a 12 volt system but there are exceptions to this rule as in the case of the starter circuit where the maximum voltage drop allowed is 0 5 volts i Throughout the procedures wherever an exception applies this figure will be clearly stated The following is the minimum equipment necessary to carry out this fault diagnosis l D C voltmeter moving coil 4 open scale 0 40 volts 2 D C ammeter moving coil 4 open scale 10 0 100 amp Note The voltmeter and ammeter can be obtained in a test box form as shown 3 Hydrometer Fig 1 4 Heavy duty battery discharge tester Fig 2 5 Ohmmeter Fig 1 Fig 2 Heavy duty battery discharge tester Page 2 Contents INTRODUCTION BATTERIES STARTERS Battery check Checking the starter Checking the starter system pre engaged drives COIL IGNITION Standard coil ignition system Ballasted ignition system Opus ignition test procedure Static ignition timing Stroboscopic timing DYNAMOS AND CONTROL BOXES Battery test Checking dynamo Checking dynamo leads Compensated voltage control Ignition warning light Current voltage control ALTERNATORS Battery test 10 11 AC systems 15 16 17 18 20ACR Battery test LIGHTING Side and tail light circuit Voltage at the battery under load Headlights stop lights and drcisi indicator circuits Headlamp alignment WIPER M
54. resistor as shown in Fig 46 Caution Ensure that the voltmeter prod does not touch the resistor housing while in contact with the terminals With ignition on reading at each terminal should be battery voltage If zero reading on all terminals check supply at S W terminal other side of ballast and if zero here trace circuit back via ignition switch If zero reading on one or two terminals only replace ballast unit TEST 5 Voltage at Coil ve Re connect amplifier to ballast socket Connect voltmeter between a good earth and the coil terminal Fig 47 With ignition on the reading should be 4 6 volts A high reading indicates a faulty coil or amplifier proceed with tests Zero reading indicates a fault in the amplifier to coil lead tacho BRIT Ci ignition switch N amplifier ID solenoid Fig 46 Checking ballast resistor 9BR ignition switch Fig 47 Voltage at terminal of coil Page 23 TEST 6 Voltage at Coil ve Open Circuit Disconnect lead at coil terminal Connect the voltmeter between a good earth and coil ve as shown in Fig 48 With ignition ON meter should read BATTERY VOLTAGE Zero reading indicates that the primary winding of the coil is faulty TEST 7 Voltage at Coil ve Closed Circuit Re connect lead to coil terminal leave voltmeter connected between earth and coil Fig 49 With ignition on meter s
55. s open the voltmeter will register battery voltage Should the ignition timing be incorrect centralise the micrometer adjuster if fitted slacken the distributor clamp bolt and position the STATIC TIMING Fig 53 Static ignition timing distributor to the point of contacts about to open and re tighten clamp bolt It must be remembered an incorrect contact gap can affect ignition timing The contacts must be set and maintained at 0 35 0 40 mm 014 016 The ignition timing is now set with sufficient accuracy to be able to start and run the engine Final adjustment may be carried out using the stroboscopic timing light and the micrometer adjustment STROBOSCOPIC TIMING Fig 54 Connect the strobe H T pick up into No plug lead and disconnect the distributor vacuum pipe In the case of a separate strobe battery supply will also be required Start and run the engine at the manufacturer s specified idling speed Direct the strobe light on the timing marks and check the degrees of advance against the recommended figures The strobe light can also be used to check that the centrifugal and vacuum advance mechanisms are operating but in order to do this the figures obtained must be compared to those specified for the particular vehicle These figures are quoted in the engine manu facturer s workshop manual Timing marks and their positions will vary with different types of vehicles These are normally quoted in the vehic
56. same voltage as the battery voltage under load 1 ignition on contacts closed it proves that the supply from the battery to the ignition coil is satisfac tory On the other hand zero low voltage indicates a fault between the battery feed and the terminal in which case this circuit must be checked back to the source of supply Note All tests are for negative earth systems It should be remembered that in a positive earth system the supply side of the ignition coil is the terminal Page 16 TEST 4 Voltage at Terminal of Coil Contacts Open Next the primary winding is checked for con tinuity The contact points must be open A voltmeter is connected between the terminal of the coil and earth Fig 27 When the ignition is switched on the voltmeter should register battery voltage If a zero reading is obtained it indicates 1 The primary winding of the ignition coil may be open circuit or 2 There may be a short circuit to earth in the dis tributor or in the coil distributor lead To help ascertain the actual cause of failure the lead from the L T terminal of the coil is disconnected and another voltmeter reading is taken a If a zero reading is obtained there is a break in the primary winding b If the voltmeter registers battery voltage the short circuit is either on the coil to distributor lead or within the distributor EARTM AT ENGINE Fig 2
57. t dry cloth paying particular attention to the space between the electrodes If the cover is tracked shown by a thin conducting track of burned bakelite between the electrodes or to earth it should be replaced The condition of the H T cables especially the insulation is then checked When the insulation shows signs of cracking or perishing the cables must be renewed Special care must be taken to maintain the correct firing order when replacing the H T cables HT LEAD FROM COIL PLUG LEAD Fig 33 Checking the distributor cover and leads CONTACT BREAKER ASSEMBLY AND GAP SETTING Fig 34 The contact breaker must be maintained in good condition Ensure that the contact surfaces are free from oil and grease If the contacts show signs of excessive wear they should be replaced When setting the contact breaker gap ensure that the contacts are fully open i e the contact heel is on the peak of the cam lobe A gauge of the appropriate thickness 0 35 0 40 mm 0 014 0 016 should make a sliding fit between the contacts It is advisable to re check the gap after adjustment to ensure no movement has taken place while the screw was being tightened Providing the distributor is in good mechanical condition an alternative method of setting the contact gap is to use an accurate dwell angle meter CONTACT BREAKER ADJUSTMENT FOR 35D DISTRIBUTORS The contact breaker setting is adjusted by rotat
58. the ignition system a quick method of checking the battery is as follows Switch on headlights and ignition and operate the starter If the engine is turned over at a reasonable speed and the lights remain fairly bright they will dim slightly we can assume that the battery will supply sufficient current for us to be able to carry out the ignition test procedure Should the lights dim excessively and the starter appear sluggish the complete test procedure must be applied to the battery i e hydrometer and high rate discharge TEST 2 Check for H T Sparking This test is to ascertain whether a good H T spark is being produced Remove the main H T lead from the distributor cap and hold the end of the cable approx 6 mm 0 25 from the engine block see Fig 25 Switch on the ignition crank the engine and check for regular sparking If regular sparking occurs this suggests a fault other than coil output i e plugs fuel system timing etc but if sparking does not occur proceed with following tests CHECKING THE PRIMARY CIRCUIT TEST 3 Voltage at Terminal of Coil Contacts Closed A voltmeter is connected between the terminal of the ignition coil and a good earth point for example the engine block or chassis see Fig 26 It is preferable for the contacts to be closed during the test so that current is flowing through the primary winding The ignition is then switched on If the voltmeter registers the
59. tor should be run for a few minutes to en sure that the tests are carried out at the normal operating temperature Then stop the engine a Disconnect the battery earth cable b Connect an ammeter between the starter solenoid terminal and the alternator main output cable Fig 79 c Remove the connections at the alternator and the moulded cover Then re make the connections Use a jumper lead to short together the F and connections of the voltage regulator unit 8TR Green lead and black lead i e earth 8TRD Green lead and earth LI TR IATR Regulator frame and earth d Re connect the battery earth cable e the ignition or auxiliary switch for diesel vehicles and check that the warning light comes on f Start the engine and slowly increase speed At approx 3 000 engine rev min the ammeter reading should equal the maximum rated output of the alternator Alternator Model Ammeter Reading 15ACR 28A 16ACR 34A 17 36A 17ACR De rated 25A 8 43 20ACR 66A Note If the ammeter reading is low the alternator is at fault TEST 6 Checking Voltage Drop in Charging Circuit Use a voltmeter to check for high resistance in the charging circuit see Fig 80 a Connect a voltmeter between the battery insulated terminal and the alternator main output terminal b Switch on the vehicle lighting load headlamps on main beam Start and run engine at appro
60. ve brush position to which the supply is connected when the higher speed is required A further feature of this unit is dynamic or regenerat ive braking when the wiper switch is moved to the park position The control for this operation is on the gear box casting These motors are also available in self switching or self parking versions The self switching unit will stop at the end of its normal wiping arc The self parking motor when switched off will reverse its rotation operate an eccentric coupling and extend its length of stroke to park beyond the normal wiping arc usually off the screen m COLOUR _ s YELLOW KE 75 aeo Fig 88 Wiper motor test plug Page 42 WIPER TEST PROCEDURE Testing of wiper switching and circuits could become an exceedingly complex procedure We therefore recommend a quick but simple method of establishing whether the fault lies in the wiper motor itself or the switching This involves the use of a made up test plug The plug is the common wiper plug easily obtainable as used on all present day permanent magnet motors connected with four leads red blue yellow and white as shown in Fig 88 Note Plug connections and 2 should be linked at rear of plug blue lead Remove the wiper motor plug on the vehicle and insert the test plug By connecting a 12V supply with ammeter in series across the various combinations o
61. x 3 000 rev min The voltmeter reading should not exceed 0 5V c Transfer the voltmeter connections to the battery earth terminal and the alternator body d Start and run the engine as in b The voltmeter reading should not exceed 0 25V Note If the readings are higher then there is a high resistance in the circuit which must be located and rectified TEST 7 Checking Voltage Regulator Setting Before checking the voltage regulator setting it is essential that a battery in a well charged condition is fitted to the vehicle a Disconnect the battery earth cable b Connect an ammeter between the starter solenoid terminal and the alternator main output cable Connect a voltmeter across the battery terminals Fig 81 Fig 79 Checking alternator maximum output SOLENOID ALTERNATOR Fig 80 Checking voltage drop in charging circuit SOLENOID Fig 81 Checking voltage regulator setting c Re connect the battery earth cable d Start and run the engine at approx 3 000 rev min until the ammeter reading is less than 10 amperes The voltmeter reading should be within the limits 13 6 14 4V If the reading is unstable or outside the specified limits the voltage regulator is faulty and should be replaced Note When checking battery sensed alternators first check for high resistance in sensing lead Connect known good lead between battery ive terminal and alternator terminal B and repeat

Fault Diagnosis Service Manual

Contents

Download Pdf Manuals

Related Search

Related Contents