Conventional Rack and Pinion Power Steering Operation
Contents
1. December 2000 Volume 2 No 12 Magnasteer power steering is now available on a wide range of cars from all tive GM divisions Magnasteer is an electronic device added to conventional power rack and pinion steering to vary the amount of effort required to steer the car depen dent on vehicle speed At low speeds steering effort is lower for ease In park ing AS speed increases steering effort is increased for greater road feel Additionally on some models evasive steering maneuvers also affect steering effort Conventional Rack and Pinion Power Steering Operation An understanding of Magnasteer begins with an explanation of conven tional power steering In a conventional power rack and pinion steering gear the steering input shaft is joined to the pin ion by a torsion bar inside the valve body Whenever the steering wheel is turned the torsion bar twists slightly a degree or two as the steering effort is applied through the pinion to the resis tance offered by the front wheels The two halves of the spool type hydraulic control valve are attached one at each end of the torsion bar So when the tor sion bar is twisted the spool halves are realigned relative to each other and fluid is permitted to flow through to the steer ing gear Steering effort determined by the stiffness of the torsion bar and pump flow is constant at all times Magnasteer Operation In a car equipped with Magnasteer th2. 2000 Chevrolet Cavalier Malibu 2000 Oldsmobile Alero 2000 Pontiac Grand Am Sunfire TRANSMISSION TRANSAXLE 00 07 30 017 Allison Automatic Series 1000 Transmission Exchange Program Early Concern Detection 2001 Chevrolet and GMC C K 2500 3500 Pickup Models with Allison Automatic Series 1000 Transmission RPO M74 BODY AND ACCESSORIES 00 08 42 007 Stop Tail Lamp s Inoperative or Intermittent and or Water in Lamp Replace Circuit Board Gasket and or Lamp Assembly 1997 1999 Chevrolet Malibu 1999 2000 Pontiac Grand Am 00 08 49 011 Availability of Smoker s Package 2001 Chevrolet Venture 2001 Oldsmobile Silhouette and 2001 Pontiac Montana 00 08 50 014 Driver s Bucket Seatback Movement During Braking Replace Seatback Recliner Assembly 2000 Chevrolet and GMC C K Pickup Silverado and Sierra and Utility Suburban Tahoe Yukon Yukon XL Models 00 08 52 004A Intermittent Operation of Remote Keyless Entry System Replace Instrument Panel Cluster 2000 Chevrolet Impala Monte Carlo 00 08 61 003 Clunk Pop Noise From Front Of Vehicle Shim Rear Frame Cradle Mounts 2000 Chevrolet Impala Monte Carlo 00 08 110 004 Rear Quarter Trim Gaps to the B Pillar Insert Screw 1998 2000 Chevrolet Camaro coupe 1998 2000 Pontiac Firebird coupe Thanks for the Information GM Service Operations sent out a questionnaire asking about the Tech 2 and Electrical service Information in late September to
3. Diagnostic Assistance and Parts Restriction Program for Delphi Chassis Suspension Components 1999 Chevrolet and GMC C1 K1 Models Silverado and Sierra with MSR Manual Selectable Ride RPO ZX3 00 03 08 003 Revised Lower Control Arm Removal Installation Procedure and Fastener Tightening Specifications 1997 2000 Chevrolet Malibu Oldsmobile Cutlass and Alero Pontiac Grand Am 00 03 10 003A General Motors Tire Warranty 1996 2001 Passenger Cars and Light Duty Trucks BRAKES 99 05 25 003A Cancellation of DBC 7 Diagnostic Assistance and Parts Return Program 1999 Buick Century Regal 2000 Chevrolet Cavalier Impala Malibu Monte Carlo Venture 2000 Oldsmobile Silhouette 2000 Pontiac Sunfire Montana ENGINE PROPULSION SYSTEM 99 06 01 002E Exchange Program for 2001 Model Year 2001 Chevrolet and GMC C K and G Light Duty Models Chevrolet and GMC B7 C6 C7 Medium Duty Models with 8 1L Engine VINs E G RPO L18 00 06 01 022 Engine Noise Replace Belt Tensioner 1999 2001 Chevrolet Tracker with 2 0L Engine VIN C RPO L34 00 06 03 008 Battery Testing Using Essential Tool J42000 Battery Tester 2001 Corvette 00 06 04 042 Malfunction Indicator Lamp MIL On With DTC P0446 Set Reprogram PCM 1998 2000 Chevrolet and GMC K K Models with 7 4 L Engine V N J RPO L29 with California Emissions NB6 00 06 04 044 Engine Hesitates Stalls and or Will Not Start Replace Modular Fuel Sender Strainer
4. thorough the electromagnet and the magnets begin to repel each other The more the magnets repel each other steering effort decreases as though the torsion CENTER bar became MAGNET w lighter This Low speen Pras ste condition at low road speeds such as parking CENTER At PERMANENT x about 45 m a mph there HIGH SPEED POLE iS NO Cur rent flow through the magnetic coil so steering effort is determined only by the torsion bar and pump flow Above 45 mph current flows in a positive direction and increases as speed increases The electromagnetic pole pieces and the permanent magnet attract each other which raises the torsional rate of the steering gear and adds to steering effort It s as though the torsion bar gradually became stiffer This pro vides greater road feel An added feature on some Magnasteer systems comes into play in a skidding condition If excessive lateral G forces are detected Magnasteer increases steering effort to encourage the driver not to oversteer Magnasteer MAGe The latest version of Magnasteer elim inates the permanent magnet In this form one pole piece of the electromag net is mounted to the input shaft and the other to the pinion shaft At the lowest speeds there is no current flow through the electromagnet and steering effort is dependent only on the stiffness of the torsion bar As speed increases current flow through the electromagnet increas es a
5. In 2000 Tracker design changed to a hub centered wheel which eliminated the vibrations caused by off center mounting of the wheel The Tracker how ever continues to be sensi tive to tire induced vibra tions and customers may benefit from following the TPC Specification recom mendation Steering Wheel Shake Vibration After Tire Rotation After tires are rotated steering wheel vibration ing the evaporator core some of the bolts retaining the cross vehicle beam to the hinge pillars can not be removed due to contact with the windshield The bolts are approximately 8 10 inches in length About 3 4 inches will concerns may suddenly reappear The 1999 Tracker uses a lug centered wheel and relies upon the lug nut taper to wheel hole taper interface to center the wheel and tire assembly on the hub Steering wheel vibrations induced by off center wheel instal lations may be significant ly reduced with the fol lowing proce dure Start by ensuring that tire alr pres Sure IS Cor rect Balance the wheel and tire assembly using elec tronic balancing equipment which also measures radial force variation Wheel and tire assemblies which have a radial force varia tion reading of greater than 9 pounds should be evaluated for cause and may require replacement of the wheel or tire Follow this procedure to install wheel lug nuts to aid in centering the wheel on the hub Rotate the hub to posi
6. section of the service manual presents a test proce dure for the Magnasteer hydraulic com ponents which are the same as those used in non Magnasteer systems Use of tester J 44721 permits you to test the operation of the steering gear and the pump and identify system restrictions Ken Hill and Scott Bower contributed to this article GM TechLink is a monthly magazine for all GM retail technicians and service consultants providing timely information to help increase knowledge about GM products and improve the performance of the service department This maga zine IS a companion to the GM Edge publication VSSM Communications Gracemary Allen Publisher amp Editor Mark Stesney GM Service Operations lt sMark Stesney GM com Technical Editor Jim Horner lt sJim Horner SandyCorp com 1 248 816 3641 Production Manager Marie Meredith Desktop Publishing Greg Szpaichler MediaWurks ds spake mediawurks com FAX number 1 248 649 5465 Write to gt lt TechLink PO Box 500 Troy MI 48007 0500 General Motors service tips are intended for use by professional tech nicians not a do it yourselfer They are written to inform those techni clans of conditions that may occur on some vehicles or to provide informa tion that could assist in the proper service of a vehicle Properly trained technicians have the equipment tools Safety instructions and know how to do a job properly and safely If
7. tion two studs of the five at the top of the circle and OE information for the 1999 Tracker remain in the hole when they contact the windshield The windshield will need to be removed to complete the repair Take care to avoid breaking the windshield during removal GM Technical Assistance parallel to the road sur face Place the wheel on all five studs and spin on the top two lug nuts finger tight Rotate the wheel 180 so the opposing one stud is at the top of the circle and spin the lug nut on fin ger tight Using hand tools tight en these three points of the lug nut pattern to just past finger tight which will center the wheel on the hub Install the remaining two lug nuts and using a star pattern evenly torque all lug nuts to the correct value Steering Wheel Shake Vibration After Tire Replacement The OEM tire has a Tire Performance Criteria Specification TPC Spec number on the sidewall Replacement tires should carry the same TPC Spec number If not different or unwanted ride characteris tics such as steering wheel shake or vibration may be induced Don Sherman con tributed to this article Model Brand Tire Size Pressure TPC Spec Treadwear Traction Temperature 2WD Goodyear P195 75R15 26PSI 1043MS 340 B B base Wrangler 180 kPa ST 4WD Uniroyal P205 75R15 26PS I 1031MS 480 B B base Tiger Paw 180 kPa Service Bulletin Based on TechLink Reader s Informat
8. 0 100700 40 and 22 degrees F a change of 18 degrees is 48 000 ohms The change between 194 and 212 degrees also 18 degrees is only 64 ohms All thermistor based sensors have two wires Circuit basics can be explained using the IAT diagram The PCM supplies a 5 volt signal through a dropping resistor and out to the IAT on the tan wire The IAT provides a ground path through the sensor and back to the PCM on the black wire Note that this sensor ground is often shared by other components and can be influenced by a shorted con dition within them Return to page 1 Lil SEMSOR J72 TAM ETA 457 BLE TO TPS AND ECT When the IAT sensor is very cold high resistance it acts like a roadblock for the flow of electrons to ground The IAT sensor signal in the PCM is high As the IAT sensor heats up the resis tance drops and more voltage is dropped across the sensor The circuit is very simple Circuitry on a thermistor based sen sor IS very easy to test On a cold engine one that has not run within six LAGHE COOLANT TEMPERATURE SENSOR da FEL hours scan data for ECT and IAT should be within ten degrees Fahrenheit If a malfunction in the circuit is sus pected observe the scan tool parame ter with the sensor unplugged The unplugged sensor will create very high infinite resistance and the scan tool should show a very cold temperature approximately 40 degrees Fahrenheit If this doe
9. a con dition is described do not assume that the bulletin applies to your vehi cle or that your vehicle will have that condition See a General Motors deal er servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information Inclusion in this publication is not nec essarily an endorsement of the indi vidual or the company Copyright 2000 General Motors Corporation All rights reserved p Return to page 1 i Power Steering Analyzer Power Steering Analyzer J 44721 a In addition to the pressure gauges the analyz er contains a flow meter to measure fluid flow under various conditions And a valve permits adding a variable restric tion to the circuit as called for in the ser vice manual procedures new essential tool has been released by Kent Moore and will be in your J 44721 permits you to test the opera tion of the steering gear and the pump and identity system restrictions that may be present in the pressure or return lines The analyzer is installed in the pres sure line between the pump and the steering gear If the system has been repaired accurate diagnosis requires that the system be bled dealership soon You ll need it to perform the power steering sys tem diagnostic procedures in the 2001 service manual The J 44721 analyzer is an updated version of the J 25323 analyzer which was previously essential for Oldsmobile
10. ake Service Club Contact Ty Johnson Jerry Seiner Buick Pontiac GMC Inc North Salt Lake UT 802 298 5163 Lance Mossman Dennis Murphy Master Technician Superior Oldsmobile Cadillac GMC Paul Richards and Richard Mcintyre owners Brighton MI George Reed Shop Foreman Asst Service Manager Fischer Chevrolet Oldsmobile Bob Fischer president Titusville FL Max Millender ASE Master Technician Ewing Buick GMC Pontiac Fin Ewing dealer principal Plano TX Jon Finefrock Master Technician Faulkner Chevy Inc Judith Faulkner owner Lancaster PA CMAT L1 Applegate Chevrolet Jim Applegate owner Flint MI Dennis Burtness Shop Foreman Burtness Chevrolet John Bowditch owner Orfordville WI Mark Haynes ASE Master Technician Steve Coury Buick Pontiac GMC Steve Coury owner Cottonwood AZ Joesph Herring ASE Master Technician Harold Chevrolet Jim Lupient owner Boomington MN Return to page 1 TAC Tips 2001 Pontiac Aztek Requires Windshield Removal To Replace Evaporator Core Some information was omitted from S12000 When remov Tracker Sensitivity to Tire Vibrations The 1999 Tracker became more sensitive to wheel and tire imbalance and tire radial force varia tion due in part to the design change to rack and pin ion steering OEM tire spec ifications and the tire and wheel match ing and balanc ing Operations at assembly were made more stringent
11. ctions 2 OE filters have a seal with a red teflon coating Non OE filters have a black uncoated seal 3 All filters have an ink stamped 6 digit Julian date code at the Testing Tips wrench flat end of the filter 065003 March 5 2000 3rd shift OE filters have an OE at the end of the date code Non OE filters do not For Chevrolet Metro and Tracker models the original filters have Suzuki printed on them and replacement filters do not On Chevrolet Prizm models the origi nal filters are black with white Japanese charac ters and a caution in English Replacement filters do not have any Japanese writing The next time rou tine maintenance comes into question identifying the engine oil filter may help you determine if scheduled maintenance has been performed Rich Burrell The power steering system section of the service manual provides a test procedure for the power steering system hydraulic components Use of analyzer fr f f f of air before beginning the test Also any air introduced dur ing the installation of the analyz er must be purged Maintain the proper level of fluid in the reser voir during the test use only approved power steering fluid The power steering system must be warmed up by allowing the engine to idle until it reaches Water Inside Rear Spoiler operating temperature The hydraulic tests require you to observe pressure and flow reading
12. dealers and available to all dealers If you already have the J 25323 you can convert it to become the J 44721 by adding the components in kit J 25323 UPD The major difference between the two analyzers is that the J 44721 is equipped with two pressure gauges instead of one for accurate read ings at both low and high pressures Also the J 44721 includes an adapter assortment that permits using the ana lyzer on all current GM cars and trucks Identifying OE Engine Oil Filters If you question whether the proper routine maintenance has been performed on a vehicle there are sev eral things to look at One way to check if routine maintenance has been performed is to identify the current engine oil filter If the vehicle still has the original equipment OE oil filter after 20 000 miles for example rou tine maintenance may not have been per formed For 1998 2001 mod els equipped with a GM Powertrain pro duced engine there are several ways you can distinguish between OE oil filters factory installed and non OE oil filters which have been installed after the vehicle was new This information applies to all vehicles except Saturns Chevrolet Metro Tracker and Prizm Cadillac Catera and 3 5L V6 LX5 engines with the PV6 cartridge type filter 1 OE filters have a small part number label 25 4mm x 35mm Non OE filters have a larger label 89mm x 60mm that includes tightening instru
13. e basic power rack and pinion steering system continues to function normally Magnasteer does not affect flow so nor mal boost is available at all times The basic Magnasteer system varies only the driver s steering effort regulat ed according to vehicle speed In current production Magnasteer is controlled by the Electronic Brake Control Module EBCM a few models in past years 4 used a stand alone module The EBCM controls current flow through the Magnasteer electromagnetic coil both the amount amperage and the direction polarity Pulse width mod ulation is used to vary the voltage and the resulting current flow Current varies between 2 and 3 amps Current flows from the controller to the Magnasteer rotary actua tor mounted i 5 POLE in the steer PIECES ing rack assembly It CTROMAGNETIC consists of iL two magnets a permanent magnet and an electro magnet The elec tromagnet receives the variable current The perma nent magnet has 30 poles spaced at 12 intervals There are two separate sets of pole continued on page 2 6M Service Operations continued from page 1 pieces inner and outer which close the magnetic field The permanent magnet sits between the inner and outer poles of the electromagnet The strength and polarity of the mag netic field in the electromagnet deter mines the effect Magnasteer has on steering Input At zero mph negative current flows
14. ed the tension needed and was held in place by the vent I m proud that the information was used by GM I m glad could help Now will all reader suggestions become bulletins Probably not But if you have a suggestion for a product condition try submitting a VME product report This system allows you to leave a voice mail message regarding any current product condition you ve come across that you think GM engineers should know more about To submit a product report call 1 888 274 4185 When you are asked to input the mailbox number use the fol lowing Mailbox 32000 Truck Mailbox 32001 Car and U Van Mailbox 32002 Powertrain GM values input from the field on product concerns Your insight can help GM increase vehicle quality and owner satisfaction Return to page 1 Bulletins November 2000 This review of service bulletins released through mid November lists the bulletin number superseded bul letin number if applicable subject and models GENERAL INFORMATION 00 0089 024 September 2000 Bulletin Summary 2001 and Prior Passenger Cars and Trucks HVAC 00 01 38 008 A C Inoperative Repair Wires and Reroute Harness 2000 Chevrolet and GMC S Truck Models With 2 2L Engine VIN 4 RPO LN2 Shreveport Assembly Prior to VIN Breakpoint Y8302995 00 01 38 009 Refrigerant Dye Added to A C System at Assembly Plant All 2001 Passenger Cars SUSPENSION 99 03 11 001A Cancellation of
15. every dealership in the U S The questionnaire was also distributed throughout GM dealerships around the world The goal was to gather feedback about the operation and use of the Tech 2 as well as GM Service Information The response has been overwhelm ing and GM Service Operations would like to say Thanks sl Se ee a Vaa db oe ee G a e i Em ees ery ee ee The efforts of everyone who completed a question naire are appreciated All of the data is being compiled and a summary of the results of both questionnaires will be put together With this feed back from actual users of the tools future product improve ments will be made based on what technicians want and Ti ee a y o e oer need your feedback Jeff Flood Thanks to all who responded to the question naires and look for more details soon about future enhancements based upon ERRATA 2001 Tire Pressure Monitor Tool An illustration in the November 2000 issue of GM TechLink was incorrect The tool number J 41760 is cor rect but this is what the Tire Pressure Sensor Programmer tool looks like Return to page 1
16. ink Service Operations would like to extend their thanks to the pre sent members of the advisory group listed here SOUTHEAST REGION Atlanta Service Club Contact Jeff Burns Jerry Brown Chevrolet Buford GA 770 945 4981 Metrolina GM Service Managers Club Contact Tommy Cross Dale Earnhardt Chevrolet Newton NC 704 465 3251 Blue Ridge Service and Parts Managers Club Contact Sam Lilly Royal Chevrolet Oldsmobile Cadillac Lynchburg VA 804 237 9400 Triangle Service Managers Club Contact Tony Crabtree Don Lacefield Chevrolet Buick Hillsborough NC 919 732 2151 Piedmont Service Managers Club Contact Jeff Keith Modern Chevrolet Winston Salem NC 336 722 4191 WESTERN REGION LOCAR Club Contact Gary Loy Cormier Chevrolet Long Beach CA 310 830 5100 Las Vegas Service Managers Club Contact Tom Hudlick Cadillac West Las Vegas NV 702 873 8888 San Diego Service Managers Club Contact Earl Ashbury Weseloh Chevrolet Carlsbad CA 760 438 1001 Inland Valley Service Managers Club Contact John Arnold Beach City Chevrolet Long Beach CA 562 597 6633 Central Coast Service Managers Club Contact Steve Montana Rio Vista Chevrolet Buellton CA 805 688 3231 Seattle Service Club Contact Roger Sideck Bill Hazelett Chevrolet Kent WA 800 638 7222 Inland Empire Fixed Operations Club Contact Dale Poole Chipman amp Taylor Motors Spokane WA 509 334 3555 Salt L
17. ion GM is listening Case in point a sug gested repair for 2000 Cadillac DeVille models was sent in to us here at GM TechLink The DeVille s right hand HVAC air out let vent would close while the blower is on high and Gary Zaffino a 21 year veter an technician at Massey Cadillac in Orlando FL had come up with the fix Zaffino suggested fabricating a shim that could be installed on the left and right side of the vent This would increase the tension on the blower door and prevent it from closing while the blower was set on high Service Operations working with Engineering investigated the condition and found that Zaffino s suggestion worked The result is service bulletin 00 01 39 001 The bulletin points out that a washer P N 5462496 should be installed between the right hand air outlet duct housing and the control lever at the pivot point in order to increase the tension to hold the air out let shut off door open This will keep the shut off door in the open position when the blower fan is on high while still allow ing the thumbwheel to rotate easily Zaffino says that when he diagnosed the condition he knew that the tension needed to be increased somehow on the air outlet door It needed just a little extra tension but there s not much space in there first tried to place foam in the vent but it would tear and it needed to be thicker Then tried fabricating a shim that was cut to size It provid
18. nd then pulling up Fred Tebbets Return to page 1 Engine Controls PERFORMANCE DIAGNOSIS Think of the best engine performance technician you ve ever worked with how is this person different trom you Likely you both have many of the same things available essential tools such as the Tech 2 and Fluke 87 DVOM absolute necessities for this type of work the same diag nostic resources such as 12000 for bulletins preliminary information and service informa tion access to Technical Assistance tor those tough cases Probably the only thing differentiating you from this person is among these four things listed in order of importance 1 diagnostic strategy THERMISTORS first in a series A thermistor is a temperature sensl tive resistor The thermistors used in GM vehicles have a negative tempera 2 knowledge of electrical basics 3 knowledge of indi vidual components 4 extra tools Here they are in detail between frequency and duty cycle analog and digital Class 2 and UART capacitance and induc tance Get the picture l l Individual Diagnostic Component Strategy Knowledge Strategy Based Diagnostics SBD along with a complete understanding of the service resources available are critical in the success of any technician These skills are the most important to learn above all else Electrical Basics Among the essen tial
19. nd steering effort increases In this version the Magnasteer effect depends entirely on road speed and there is no change during evasive maneu vers Only a highly informed driver could tell the difference between systems Regardless of which version of Magnasteer is installed on a vehicle the effect on the driver is the same steering effort is noticeably easier at low speeds and increases as the car goes faster Service Diagnosis may be required based on one of three driver concerns 1 Light steering effort at all soeeds 2 Heavy steering effort at all soeeds 3 Erratic steering effort levels at vari ous speeds Systematic diagnostic procedures are presented in the appropriate service manual NOTE The Magnasteer system on some vehicle lines can be recalibrated for steering effort using the Tech 2 There are three settings Factory More Firm and Less Firm On those vehicles where recalibration is available use this feature only at the customer s request Refer to the appropriate service manual for details The Magnasteer activator is service able only by replacing the entire steering rack assembly Individual components are not available Electronic Testing Malfunctions in the electronic por tions of the Magnasteer system are diag nosed using the Tech 2 to access diag nostic codes MAGe OUTER POLE STRAIGHT AHEAD STEERING MANEUVER Hydraulic Testing Tips The power steering system
20. s not occur check the sensor wire for open circuit voltage with a Fluke 87 It should be 5 volts Less than 5 volts indicates a short to ground condition or a bad PCM The next quick circuit check involves a test lead outfitted with two appropriate male terminals Use this test lead to jump the two sensor wires at the unplugged connector and observe the scan tool parameter This low resistance connection should yield a very high temperature 260 degrees Fahrenheit or above Failure of this test indicates ground circuit problems Don t forget the potentially shared ground paths with other sensors Thermistors rarely fail for reasons other than circuitry Terminal corrosion at ECT sensors is a common cause for failure Connector and sensor replacement is typically necessary Sensor wiring for an ECT sensor is unique Earlier we mentioned the dif ference in resistance changes on the upper and lower end of the tempera amp WOLT AEF nA a BIE i E ers P SWOLT AEF AAA AAA m T e Vi ECT NOA ikPuT ture scale In the PCM there are two paths for the 5 volt reference When the engine temperature Is below 122 degrees Fahrenheit it travels through two dropping resistors When it reach es 122 degrees Fahrenheit it transi tions to just one resistor This strategy is to maximize the accuracy of the sen sor for higher engine temperatures and was necessitated by the resistance characteristics of the sensor This res
21. s under various operating conditions and engine speeds Never close the control valve on the analyzer unless told to do so by the procedure and never leave the valve completely shut for more than 5 seconds at a time Matt Stange contributed to this article w A water sloshing sound may be heard coming from the rear spoiler of some 2000 Pontiac Grand Prix models when the trunk lid is raised and low ered If it is confirmed that water is inside the spoil er remove the spoiler and look for a small hole on both the left and right underside of the spoiler approximately 16 inches inboard from the out board tip of the spoiler and two a couple of inch es from the rear edge The small holes may be covered by pieces of tape that should be painted the same color as the spoiler Remove the tape to drain the water from the spoiler Do not retape over the holes Once the water is removed from the spoiler reinstall the spoiler on the vehicle RKE Receiver Module Location The Remote Keyless Entry RKE module receiver has been relocated on 2001 Pontiac Grand Prix models The module is now located at the cross car beam in front windshield side of the passenger side air bag It was previ ously located behind the Driver Information Center At its new location the RKE module is accessed by removing the defroster grill To remove the module it must be disengaged from the retaining tabs by moving it to the left a
22. s you need to know the relationships between volts amps and ohms schematic reading skills the differences C 90 Service manual diagnostics for individ ual components are the front line of defense You should always refer to the diagnostic charts asso ciated with various fault codes or symp toms But you ve truly mastered a compo nent only when you begin to understand the importance of the voltage level or fre quency you re about to measure or the scan data you re about to read and the potential causes for variations as you read each step Temperature vs Resistance Values approximate F Ohms 212 177 194 241 There are principles behind the names of various engine sensors and output devices You re on the road to higher understanding once you realize that a component is not just an Intake Air Temperature Sensor but a thermistor or not just an Exhaust Gas Recirculation Valve but a solenoid This type of knowledge comes from training or experi ence Extra Tools Extra tools are something you can buy any time once you understand their benefits Buying a tool before realizing its potential is a bad idea Also realize that mas tering diagnostic strat egy electrical basics and component knowl edge should come before you even con sider buying advanced tools The accompanying article is the first of calculations several to be devoted to engine controls Wi
23. th every coming article we intend to feature a specific pow ertrain input or output device We ll answer many questions Including What type of device is it What is its pur pose How is built What does its cir cuitry look like How is this com ponent best diag nosed scan tool DVOM The purpose of these articles is to help you develop the skills and knowledge you need to become the performance tech nician that others con sider the best Concentrate on whichever of these four things you need to work on to differen tiate yourself from the others Only you know what they are Engine Oil Temperature Sensor EOT affects engine oil life monitor Note the change in resistance for temperature is not linear For example the difference in resistance between ture coefficient meaning the resistance goes down as the temperature goes up Here are some thermistors used by the Powertrain Control Module PCM along with their role in PCM decision making Engine Coolant Temperature Sensor ECT affects fuel delivery idle TCC apply EGR cooling fans EVAP knock ignition control Intake Air Temperature Sensor IAT affects air density air fuel adjustments spark adjustments Transmission Fluid Temperature Sensor TFT affects TCC apply line pressure 80 176 SEZ 70 158 467 60 140 667 ONG 122 ols 40 104 1459 30 86 2238 20 68 3520 10 50 5670 32 9420 16180 28680 5270
24. to do so in some states Leave the decal in the vehicle installation is at the cus tomer s discretion Dan Oden Return to page 1 GM Service Clubs Part 2 In the November issue of GM TechLink we listed a number of GM service clubs around the country that meet to talk about the service issues that dealership service departments face each day This interactive communica tion Is one of the benefits for ser vice managers who attend a local service club meeting The clubs provide a way for service man agers to access a wide array of information from other dealership service departments as well as a number of GM sources Following is a list of additional GM service clubs GM supports local service clubs and many GM representatives attend the club meetings For more information about GM service clubs contact any ot the clubs listed here TEER as ORD alas ARO A RR eae EER a Service Operations Advisory Group GM Service Operations relies on Input from a number of sources to assess the opinions and needs otf retail dealership ser vice departments across the country One of these sources is a group of eight technicians rec ommended by their TechLine rep resentatives in the five regions This advisory group serves as a sounding board for service issues and their feedback is for warded to the appropriated department within GM for evalua tion Their suggestions may also lead to future articles in GM TechL
25. ults in an obvious shift in voltage at the 122 degree mark At that point the voltage jumps up immediately trom below 1 volt to about 3 5 volts This becomes important to know if you use a scope to diagnose an ECT circuit live or when using a scan tool on a truck product that includes ECT voltage on the data list It s unlikely that you re going to get a P0118 ECT sensor code to work on tomorrow to exercise your new knowl edge But the sooner you practice the more likely that you will retain it So get out there and give those Tech 2 circuit checks a try Be on the lookout in future issues for more articles on Performance Diagnosis Craig Blake Cruise Control Cancels intermittently The cruise control may cancel intermittently when using the left turn signal on some 2000 Buick Century and Regal models The resume function is still operational after the cruise control cancels This condition may be caused by an internal switch in the multifunc tion lever causing a backfeed to the cruise control module The module thinks it has seen a brake switch input signal and cancels the cruise control set speed If this condition is verified replace the multifunction lever Parts are available through GM SPO Wayne Zigler Xtreme Pickup Truck Decal Installation Xtreme models are shipped with an Xtreme decal that fits the wind shield This decal should not be installed during pre delivery because It may not be legal
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