Automotive engine electronics  how to diagnose and repair the automotive computer control system

Automotive ICS DR b b How to dLgnose and repair the automotive Compufer Control System .-rp'&.t Automotive Engine Electronics How to Diagnose and Repair the Automotive Computer Control System by Dr Robert C McElroy Second Revised Edition Accuracy Publishing, Homestead, Florida photo by Rick Bernskoetter Bob McElroy at the wheel of his Hilborn Fuel Injected Corvette at an SCCA autocross Note video camera attached to windshield Published by: Accuracy Publishing Co Post Office Box 514 Homestead, FL 33035-0514 Corvette Cover Artwork Compliments of: Micrografx Corporation 1511 I Bob McElroy Allrights reserved No part of this book may be used or reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording or by any information storage and retrieval system without prior written permission from the author except in the case of brief quotations embodied in critical reviews and articles Copyright 1987,1988 by Robert C McElroy, Ph.D First Printing 1987 Second Printing 1988, revised Third Printing 1988, revised Printed in the United States of America Library of Congress Cataloging in Publication Data McElroy, Robert C Automotive Engine Electronics Understand, Diagnose & Repair: Fuel, Ignition & Computer Control Systems Automotive Electronics Computers, sensors, etc Electricity and Electronics Computers, sensors, etc Diagnosis Computers, sensors, etc Mathematics Computers, sensors, etc I Title ISBN 0-929603-37-0 S o f t c o v e r SECTION II Driveability Diagnosis SECTION I Sensors & Systems TOPIC PAGE Table of Contents Objective Foreward Introduction About the Author Background of Today's Automobile Electrical & Electronic Terms OHM'S Law Series Circuits Parallel Circuits Series Parallel Circuits Diodes Despikeing and Clamping Diodes Transistors Point Style Ignition Systems HE1 High Energy Ignition EST Electronic Spark Timing Distributorless Ignition Systems CI CCC Computer Command Control EFI Electronic Fuel Injection PFI Port Fuel Injection Transition fuel to electronic systems Throttle Position Sensor TPS Temperature Sensors CTS & MAT Manifold Absolute Pressure MAP Electronic Spark Control ESC Mass Air Flow Sensor MAF Eshaust Gas Recirculation EGR Idle Air Control IAC Vehicle Speed Sensor VSS Evaporative Emission Control EEC 11 16 18 20 21 22 24 25 26 29 31 33 35 38 40 43 44 46 47 48 49 50 53 54 55 TOPIC PAGE Driveability Diagnosis Philosophy Systems Approach to Diagnosis Electronic Control Module ECM ALCL Terminal Circuits Scanner Use Integrator & Block Learn Scanner Error Diagnostic Procedures Digital Multimeter DMM Jumper Wires & Connectors Computer Harness Adaptive Tester Diagnostics & ECM Voltage Checks Continuity Tests CHAT Basic Test Procedures CHAT Advanced Testing Procedures Advanced Circuit Testing ECM Codes Open & Closed Loop Fuel Injector Balance Test SECTION Ill -SELECTED ECM VOLTAGES &WIRE DIAGRAMS Which can be read with CHAT Note: CHAT will interface BCM and GMP4 design ECMs BCM and GMP4 circuits have not been included in this publication CCC and EFI systems incorporating "edgeboard"connectors were not included CHAT is covered by U.S Patent No 4,690,475 and is available from Diagnostic Products Co P.O Box 1136, Homestead, Fl 33090 Diagnostic Products Co.is the Electronics Subsidiary of Spectra Investments Ltd Inc Objectives of this manual: Provide a comprehensive general explanation for electronically spark controlled and fuel injected engines manufactured by GM Provide specific information for the use of ALCL "scan" tools Provide specific information for the use of "CHAT' the Computer Harness Adaptive Tester Provide specific information for the use of CHAT to perform voltage and continuity testing for all wires and circuits interfacing the ECM This manual has been prepared for: Professional Technicians in the field of automotive repair Students of Automotive Technology Automotive Enthusiasts who wish to know more about contemporary automotive engine electronics This manual has been prepared with a "systems" approach: Diagnosis and repair must be performed in a step by step method, to ensure that you "isolate" the problem, and not simply replace what seems to be wrong Automotive systems are broken down so that you can see how they are intended to work in a conceptual method When you understand the general concept you will be able to apply your understanding to systems and components which differ from those included in this manual This manual is not intended to replace applicable service manuals pertaining to the service of any automobile This manual is intended to complement service manuals specificallyprepared by the vehicle manufacturer In order to understand the complex nature of today's automobile we must be able to speak and understand the language used to describe these vehicles You may be reluctant to want to learn anything, but you have made it this far by purchasing this book A book which you can use and learn new technology from A book written to help you each and every day on the job Always try and the job right the first time even if it takes a few extra minutes One good example would be a water pump If it leaks then you will probably have to the whole job over and I don't know of anyone who wants to redo a water pump The same sort of thinking applies to this new technology If the car still has a driveability problem then it is going to be a comeback and rechecks eat your earnings Actually, when you start to dig into this material it will be fun and interesting The trick is to just take your time and master these basic terms and concepts One thing that you really need to is understand how these things work, at least on a simple level This book will approach everything on a simple level and use this basic principle of understanding to build upon Some of the things which we will look at in the beginning will seem too simple to really work with However, I have seen too many repairs done incorrectly When you really analyze what you are doing the bottom line really must be to get the car fixed Hopefully, this will happen the first time or else you will have a recheck to perform Rechecks mean that you will not be making money on the next car waiting for you Therefore, the fewer rechecks the more money you ought to make That seems simple enough, doesn't it? NO RECHECKS This book has been prepared with the objective of presenting basic concepts which apply to the modern automobile which uses a small computer or ECM to control fuel delivery to the engine In order to understand how this system functions, you will be presented the basic concepts relating to how air and fuel management is accomplished If you know and understand the relationships between the sensor inputs and computer outputs you will be able to diagnose problems which occur with the modern automobile No one book can be expected to provide all information which can apply to all situations However, the information provided will be of value when you must diagnose and repair these vehicles Your use of a definite method of analysis will increase your productivity and reduce the number of comebacks and your number of rechecks This increase in productivity will make you a better technician which should also correspond to an increase in your paycheck In order that you understand how this system works we will first investigate the ignition system Understanding of today's ignition systems is 100%essential Proper fuel delivery to the engine is based upon this input signal and without it the vehicle will not run due to loss of both spark and fuel delivery As you gain experience with computer equipped cars and trucks you will find that they perform and react in a predictable way There are certain things which you must know and understand Some things must work or the vehicle simply will not run These facts will be covered so that you will be able to NO WRENCHES ON quickly and accurately determine if THE RED TERMINAL these necessary inputs are present Use of a definite strategy will mean that your diagnosis is done quickly and in a logical Always remove the ground cable first If you procedure accidentally hit some sheet metal you will not risk blowing up the battery I believe that many technicians not have a good understanding of how ignition systems operate Therefore, we will study a conventional point-type ignition first If you know and understand how this system works you will not have any difficulty with electronic systems More cars are being designed each year without distributors As you progress through your study of this book, you will clearly come to understand why a distributor is not needed As you learn how these systems operate and how other inputs can provide the same necessary signal you will be able to figure out and troubleshoot systems which you have not personally worked on yet As you study this manual and compare its information to the cars which you work with daily you will become a better technician Additional education at your local technical school or community college will also help you to be more professional in your duties If you are not already certified by ASE, you are encouraged to participate ASE certification is a highly desirable goal and those technicians who wear the ASE patch take pride in their accomplishment You make your living as a technician Vehicles which you work on daily are highly complex and the more you know about these vehicles the better off you are Your need for technical literature and education have never been greater You demonstrate your professionalism when you wear the ASE certification patch YOUR TECHNICAL JOB THE MORE YOU KNOW THE MORE THINGS YOU CAN FIX FASTER & MORE RELIABLE EVERYONE BENEFITS FROM TECHNICIAN CERTIFICATION SUPPORT IT! I walked into my local Chevrolet dealer and asked for a job as a junior mechanic and grease monkey during my summer break from college in 1969 That did not last long; soon I was tearing apart engines and trying to figure out how to get them running again The more things which I could fix, the more work I got in the shop equipment When you know what you are supposed to do, and you it well, then you can really enjoy what and how you things I would hope that you personally feel that way about your occupation if you not then I hope that this book will help you to gain this type of confidence I drove my first race car in 1965 It was while I was a senior in high school in State College, Pennsylvania We even raced in the winter I remember trying to run over a snowbank during one event while racing on the icy surface This interest in racing has probably been the key to why I have always kept a strong interest in automotives For a period of three years I was in the position of resident engine instructor, at one of the 31 GM training centers in operation at that time, after having been recruited by General Motors in 1983 In Detroit we would be given product information which would be used to conduct classes about new engine systems and their operation for dealership technicians who would attend our classes All this new information was great, but this information had to be passed on to the fellows and an occasional lady who actually "turns a wrench" to make a living It really was a lot of fun Over the years I have raced many different types ofvehicles including the likes of jeep, ferrari, pantera, vega, corvair, mustang, police cars, and my favorite, the corvette Those police cars came from when I taught High Performance Driving to police officers at the Texas Transpor- Additional qualifications to be your autation Institute thor to write this book besides my experience with GM, racing, and having been I have always felt that if you are going to a "Chevrolet Certified Technician" win on the track then you must field the would include formal college education best car Even if you happen to be the background of a BS, MA, and finally a best driver around, if your machine is not Ph.D in industrial education from Texas set up properly then you cannot win I A&M University In 1987 I was one of have never gone to an event with the idea 375 people inducted into the Automoto lose Of course I don't always win and bile Hall of Fame in Midland, Michigan I get beat sometimes, but I don't lose as an "ASIA/ASE 'World Class' TechniIt really is a state of mind where you feel cian" for holding all 16 ASE area certificonfident about your ability and your cations Way back in the old days, pre-computer cars that is, we basically concerned ourselves with three types of problems: 1) fuel, 2) ignition, or 3) mechanical However, today there is an additional 4) electronic problem area which really gives technicians a tough time This latest addition to our problems is the most difficult to understand You simply cannot take apart a transistor with a 9/16" or lOmm wrench Since you cannot easily disassemble this electronic stuff it means that you will probably have to learn about these things either on your own or in a class somewhere This book will help you understand how automotive electronics work and this book will help you fix today's electronically complex cars When cars were simple it was not too difficult to figure out which area theproblem was in and then it could be attacked If there was a question about ignition, then did spark come out of the plug wire? If not then points were pretty easy to fix I remember a 1970 LT-1 corvette at the dealership, the ticket said "won't run" I found the car, it would crank but not start I popped off a plug wire and it on top of the air cleaner wingnut; crank engine again and no spark but the 12 volt test light says power to the coil and a good ground Hmmm the points must be locked up Off with the chrome shroud, remember this is a corvette, off with the distributor cap what the So much for my first introduction to transistorized ignition Today's cars may affect you the same way There is no denying that cars are much more complex than ever before and there is no alternative to understanding how they operate Because of Federal regulations for improved fuel and emission characteristics of our vehicles it became necessary to develop more sophisticated engine control systems to meet these new standards Many of you reading this book look favorably on the past but you know that "simple" cars are no longer built; also you know that the carburetor is in fact only a "calibrated leak" which will not the job today Microprocessors are the heart of the computer or Electronic Control Module, ECM for short Microprocessors get information from many sensors placed all over the vehicle Microprocessors take this information and run it through the operational program recorded permanently inside the machine found on ECM VOLTAGE IDENTIFICATION CHART 3.8L TURBO GRAND NATIONAL "G"BODY VOLTAGE VOLTAGE I KEY ENG CKT ON lRuN OPEN CIRCUIT ;;:;1 I Fuel Pump Relay :;:;1 A/C CIutchControl Canister Purge Control EGR control KEY ON CIRCUIT + Battery 12v lnput A' Crank Reference Low Service Engine Soon Crank Reference High Ign ECM Fuse Mass Air Flow Sensor 1~2.2 ALCL TCC control ALCL Serial Data I ALCL Diag Terminal A9 Vehicle Speed Sensor El Not Used Park Neutral Switch $-, 11 Not Used bid Ground Fuel Injector, Cyl ID1 I Ground lD2 Coolant Fan Control Wastegate Controll 12 11.9 ( 13.7 10 12.1 Not Used lD5 EST Bypass Signal 14.5 14.5 10 Oxygen Sensor Signal Not Used EGR Diagnostic S/W Ground Power Steering Switch 12.0 13.2 12.1 Fuel Injector, Cyl 45 45 TPS Sensor Signal 4.9 4.9 TPS 5v Reference 12.0 13.2 12.1 Fuel Injector, Cyl 11.9 13.7 12.1 Battery 12v Input NOTES & SPECIAL INFORMATION :I] 121 :3] :4] :5] :8] 71 Fuel pump relay will read 12v for sewnds when ignition is switched on VoHage reading varlea Varies from 45 volt to battery volt depending upon drive wheel position Varies A h temperature Engine running voltage will be high or low depending WA/C Is on or off Note voltage change when shifted Into gear for automatic transmission Hall Effect Sensor Voltage will be low when vane Is p i n g through switch c12 C13 C14 TPS/CTS/ATS Ground C15 C16 Fuel Injector, Cyl Not Used Fuel Injector, Cyl Fuel Injector, Cyl VOLTAGE TESTING REQUIREMENTS: 1) 2) 3) 4) 5) 6) This chart is for use with a digital multimeter Engine must be at operating temperature Idle engine in 'Closed Loop" for ENG RUN voltages Diagnostic test terminal in ALCL not grounded No "Scan"tools installed "Key On" readings represent known good battery W 10 ECM VOLTAGE IDENTIFICATION CHART 4.3 L "B & G" BODY VOLTAGE KEY ION I I ENG RUN 13.4 CIRCUIT Fuel Pump Relay Not Used 12.4 1 Canister Purge Control Not Used S 13.8 Service Engine Soon ALCL Serial Data INOTEp" A1 A2 VOLTAGE KEY I ENG ! I ON I RUN ClRCUlT I Battery 12v lnput ~ 3I A4 A5 I Not Used ESC Signal A/C Signal 122 m I 4.9 4.9 ALCL Diag Terminal ~ 9I b9 5 Vehicle Speed Sensor 0 Coolant & TPS Ground BlO Park Neutral Switch b111 Not Used 1 System Ground A1 A1 1~12 c12 C13 D l NotUsed C14 C15 C16 D l Fuel Injector "B" Driver 12.2 Not Used 5 TPS Sensor Signal 4.9 4.9 TPS 5v Reference 12.2 13.7 Fuel Injector "B" Driver 12.2 13.7 Battery 12v Input NOTES 81SPECIAL INFORMATION ( I ] Fuel pump relay will read 1% for seconds when ignition is switched on [2]Voltage reading varies (31 Varies from w i l to banery w i l depending upon drive wheel posttion [4] Varies wllh temperature (51 Engine running wilage will be high or low depending If A/C is on or off (61 Note wltage change whan ~htftedinto gear for automatic transmiasion (7) Hall Efied Sensor Voilage will be low when vane is passong through switch I EGR Temp Diag - s/w h121 Not Used ( 13.8 I 12.3 113.8 I1 o PIN ( A ~ - JD y2.3 13.7 I I I I I I D13 Not Used 13.7 D l Fuel Injector " A Driver 12.2 13.7 D l Fuel Injector "A Driver 12.2 13.7 VOLTAGE TESTING REQUIREMENTS: This chart is for use with a digital multimeter Engine must be at operating temperature Idle engine in "Closed Loop"for ENG RUN voltages Diagnostic test terminal in ALCL not grounded No "Scan"tools installed 6) "Key On" readings represent known good battery 1) 2) 3) 4) 5) W 11 ECM VOLTAGE IDENTIFICATION CHART 5.OL, 5.71 "F"BODY VOLTAGE VOLTAGE CIRCUIT 12.2 13.8 Air Switch (Port Solenoid) A2 12.2 o Canister Purge 12.2 1 12.2 12.2 Service Engine Soon 13.8 I 13.8 13.8 2.5 4.3 4.9 EGR control , 4.9 I ( Ign - ECM Fuse Shift Ught M/T TCC ControiA/T ALCL Serial Data ALCL Diag Terminal 11.9 13.7 Fuel Pump Signal 13.8 63 HE1 Ground (EST ref low) I A ~1 84 b5 I Not Used Reference B6 Not Used 87 g ESC Sensor Signal A5 A6 I IA~ A8 A9 1.6 ( Vehicle Speed Sensor IAI 10 10 ~AI1 I 10 10 MAF Analog Ground System Ground 1~121 El 01 10 A/C Signal On Off Not Used Park Neutral Switch zh,, 11 Not Used 11.6 9.2 1 12.2 : i 12 MAF Sensor Input 13.8 :3,7 to C13 C14 C15 C16 D l Fuel Injectors 1-3-5-7 ~ 6Fuel lnjectors 2-4-6-8 12.2 13.8 12.2 13.8 2.1 MAT Signal c12 55 55 TPS Sensor Signal 4.9 4.9 TPS 5v Reference 12.2 13.8 EGR Diagnostic s/w 11.9 13.8 Battery 1% Input I 9.2 Burn-Off Relay Control DI2 D l Notused D l Notused 2.5 I ] Fuel pump relay will read 12vtor seconds when ignition Is switched on 21 Vonage madlng varier 3) Varies from wn to battery wn depending upon d h wheel position :4] Varier with temperature :5] Englne wnning wnage wlll be high or low depending if A/C Is on or off :8] Note wnage change when shined into gear for automatic transmission 71 Hall Effect Sensor Vonage will be low when vane is passing through switch 81 + or - 075V mee~ured betwen C13 and D l 91 OVwith circuit closed by a/c high pressure switch Battery 1% Input A3 1.6 NOTES & SPECIAL INFORMATION 1 VOLTAGE TESTING REQUIREMENTS: This chart is for use with a digital multimeter Engine must be at operating temperature Idle engine in "Closed Loop' for ENG RUN voltages Diagnostic test terminal in ALCL not grounded No "Scan" tools installed 6) "Key On" readings represent known good battery 1) 2) 3) 4) 5) W 12 ECM VOLTAGE IDENTIFICATION CHART VOLTAGE 5.OL LB9 "F"BODY VOLTAGE NOTE 1 NOTES & SPECIAL INFORMATION VOLTAGE TESTING REQUIREMENTS: [ I ] Fuel pump relay will mad 12vfor seconds when ignition is mltched on [Z] Vohage mading varies [3] Varies from 45 w h to battery wtl depending upon drive wheel position [4] Varies with temperature 151 Engine running whage will be high or low depending If A/C Is on or off [6] Note whage change when shied into gear for automatic transmission PI Hall EffectSonsor Vonage wlll be iow when vane is passing through switch 1) 2) 3) 4) 5) 6) This chart is for use with a digital multimeter Engine must be at operating temperature Idle engine in "Closed Loop" for ENG RUN voltages Diagnostic test terminal in ALCL not grounded No "Scan" tools installed "Key On" readings represent known good battery ECM VOLTAGE IDENTIFICATION CHART 5.7L LB9 "Y"CORVETTE VOLTAGE KEY ENG PEN loN 1RuNfkT.I 13.9 cmcunA1 Air Switch Port Solenoid A2 13.9 12.4 13.8 12.2 Canister Purge Control 12.4 13.8 12.2 EGR Control -.1 13.8 12.2 Service Engine Soon 13.3 13.6 12.1 Ign ECM Fuse 12.4 13.8 M/T Ovedrive or A/T TCC Control ~ALCL Serial Data 14.9 5 0 1 1.1 ~ALCL Diag Terminal Vehicle Speed Sensor MAF Sensor Ground NOTE Fuel Pump Relay 12.4 14.9 I Ground A3 A4 A5 A6 KEY I ENG OPEN RUN CKT ON I IN b1 I VOLTAGE CIRCUIT I 11.9 Battery l2v lnput - - 12.1 Fuel Pump Signal 13.9 EST Reference Low 0 Distributor Reference I~7 ~ 81 ~ 9I A10 A1 1~12) 12.2 Not Used C s11 Park Neutral Switch &: 12.3 13.7 0 NotUsed MAF Sensor Input 2.5 NOTES & SPECIAL INFORMATION VOLTAGE TESTING REQUIREMENTS: [I] Fuel pump relay will read 12vfor seconds when ignition is switched on (21 Voilage reading varies [3]Varies from 45 van to battery volt depending upon drive wheel position 141 Varies with temperature [S] Engine ~ n n i n wnage g will be high or low depending if A/C Is on or off 161 M e Mitage change when shiftad into gear for automatic transmisrrion Hall E f f d Sensor Vonagewill be low when vane is parsing through Jwitch 1) 2) 3) 4) 5) 6) m 13.7 4- This chart is for use with a digital multimeter Engine must be at operating temperature Idle engine in "Closed Loop" for ENG RUN voltages Diagnostic test terminal in ALCL not grounded No *Scanu tools installed "Key On" readings represent known good battery W 14 ECM VOLTAGE IDENTIFICATION CHART 5.7L "Y"CORVETTE 1985 VOLTAGE I I CIRCUIT NOTE Fuel Pump Relay 1 112.2 10 Canister Purge ~ 3I I 12.2 13.8 ,, 2.5 4.3 4.9 4.9 Shin Ught M/T TCC Control AD ALCL Serial Data ALCL Diag Terminal 6 Vehicle Speed Sensor 0 MAF Analog Ground 0 I System Ground A6 ~ J A8 A9 A10 A1 I KEY I I IN ENG I RUN Battery 12v Input 11.9 13.7 82 Fuel Pump Signal 13.8 b3 10 HE1 Ground (EST ref low)l - 64 EST Control 1.3 B5 ~6 Reference (EST Ref Hi) 1.6 B7 ESC Sensor Signal 88 sg - Not Used A/C Signal 9.2 9.2 13.8 12.2 o off On o Not Used 10 11 MAF Sensor 12 Not Used Park Neutral Switch IAI ON CIRCUIT Bl - - EGR Control VOLTAGE zk - I - - 0 12,3 13,7 2.5 - to I 8 NOTES SPECIAL INFORMATION [ I ] Fuel pump relay will read 12v for seconds when ignition Is witched on [2] Voitage reading varier [3] Varies from vok to battery volt depending upon drive wheel position [4] Varies with temperature [5] Engine mnning voltage will be high or low depending If A/C is on or off [6] Note witage change when shifted into gear tor automatic transm~ssion [7] Hall E f f d Sensor Voltage will be low when vane is passing through switch [8] + or 075V measured between C13 and D l [Bl OV with c~rcultclosed by a/c h ~ g hpressure svntch - VOLTAGE TESTING REQUIREMENTS: 1) This chart is for use with a digital multimeter 2) Engine must be at operating temperature 3) 4) 5) 6) Idle engine in "Closed Loop" for ENG RUN voltages Diagnostic test terminal in ALCL not grounded No "Scan" tools installed "Key On" readings represent known good battery W 15 ECM VOLTAGE IDENTIFICATION CHART 2.5 L S I T TRUCK M VAN VOLTAGE VOLTAGE NOTE 1 3.5 1.2 2.5 2.2 45 45 4.9 4.9 11.9 13.7 (211 Manifold Air Temp Sensor C12 C13 TPS Sensor Signal C14 TPS 5v Reference C15 Not Used C16 Battery 12v Input MAP Sensor Signal NOTES & SPECIAL INFORMATION [ I ] Fuel pump relay will read 12vfor seconds when ignition is switched on [2] Voltage reading varies [3] Varies from 45 volt to batiery wH depending upon driva wheel position [4] Vatim with temperature [SJEnglne ~ n n l n voltage g will be high or low dependlno If AIC Is on or off [6] ~ o i voltage e change when shntez Into gear for aulo~atlc'transmission [7] Hall Ened Senaor Voltage will be low when vane Is passing through switch Dl2 ~ ~ 015 DI Not Used NotUsed Not Used Not Used Fuel Injector "A" Driver 12.2 13.7 VOLTAGE TESTING REQUIREMENTS: 1) This chart is for use with a digital multimeter 2) 3) 4) 5) 6) Engine must be at operating temperature Idle engine in "Closed Loop" for ENG RUN voltages Diagnostic test terminal in ALCL not grounded No "Scan" tools installed "Key On" readings represent known good battery W 16 ECM VOLTAGE IDENTIFICATION CHART 4.3L, 5.OL, 5.7L, 7.4L TRUCK VOLTAGE KEY ION I I ENG RUN 13.4 CIRCUIT CIRCUIT NOTE Fuel Pump Relay A1 Not Used A2 VOLTAGE Not Used - - - Voltage Monitor (fuel pump) HE1 Ground (EST ref low) 0 13.9 12.4 1;1 1 13.3 13.6 12.2 4.9 ( TCC ( 13.8 ; :1 1 ~ 6I Ign ECM Fuse Control or M/T shift light 5i:i ALCL Serial Data 4.9 ALCL Diag Terminal Vehicle S ~ e e d Sensor 1o 1o - - - - [MAT &TPS Ground IAI i l 1~12 Not Used c12 C13 C14 45 TPS Sensor Signal 4.9 4.9 TPS 5v Reference Not Used 13.7 A10 System Ground 45 11.9 - IA~ Battery 12v Input 10 Park Neutral Switch 11 Not Used b121 Not Used 2; ,, 12,3 I C15 C16 NOTES & SPECIAL INFORMATION VOLTAGE TESTING REQUIREMENTS: [I] 12v for reconds on 4.3 & 5.0 Land 20 seconds for 5.7 & 7.4 L [2] Voltage reading varies [3]Varies from 45wll to baliery voh depending upon drive whwl position [4] Varies with temperature [5] Voiiage measured between C13 and A1 (+ or - 05 V) [6]Note voltage change when shmed into gear for aulomatic transmission Also, darmshM control on THM 400 [7] Except 4.3 L M & G van this system is wired at opposlte ends [B] Nd used on 7.4L 1) 2) 3) 4) 5) 6) This chart is for use with a digital multimeter Engine must be at operating temperature Idle engine in "Closed Loop" for ENG RUN voltages Diagnostic test terminal in ALCL not grounded No "Scan" tools installed "Key On" readings represent known good battery 3.8L "C& H" BODY TWROTTLE POSITION SENSOR OXYGEN SENSOR CR(3UND -5s nm n o w VMCLE -u VE-E WEED SPEED - LCM FLn€ I - SENSOR I - ru-c a+ LINK MTTERY '=L - KIN SWITCH CRANKIRUN m m w o Pi CONSTANT BATTERY MLTACC mi PARK CYLI-R YLCCT CYLMER GROUND CIH 5w RUN -mnz A I C FMI EDR CANISTER P V RCONTROL RELAY CC A I C RELAY L5 C M A F TCC POWER STCEWNa PR stw F U n PUMP C NJCCTOR I SWTCHEO #-I- R/C DRSH SWITCH rI R/C OH S I G M L F-.J$ P O K R STEERING PRESSURE SWITCH 3.8L "C& H" BODY t I POWER SlEERW3 PRESSURE SIW ECN FUSE R/C CLUTCH COMROL , ;En* E6R DIRGHOSTIC SWITCH E6R COHTROL S U I T C H CRHISTER PURGE URLUE "SERUICE EHGIHE "SERUICE EHGIHE SOOH- L I G H T GAUGES FUSE IGH T R BR8KE SWITCH 3RD 6ERR S V I T C H TCC COHTROL D 87 I - I T H GERR I CRH SIGHRL IGHITIoH I : : : CONTROL FRH CONTROL ECM @ "C" CRR W I L L USE RESISTOR JUMPER WIRE W I L L BE USED ! TRRHSllISSIOH 4TH GERR SWITCH % -I - HIGH PRESSURE SWITCH COWRESSOR CASE GROUtQ E C FUSE ~ ECM MAGNETIC PICKUP & IGNITION MODULE EST REFERENCE BYPASS GROUND IAC VALVE IAC COlL "A" HI IAC COlL "A" LO IAC COlL "B" HI IAC COlL "B" LO OXYGEN SENSOR SIGNAL OXYGEN SENSOR GROUND ENGINE GROUND INJECTOR DRIVE INJECTOR DRIVE EGR DIAGNOSTIC TEMP SWITCH PARK NEUTRAL SWITCH (A/T) VEHICLE SPEED SENSOR A/C SIGNAL 5.0LITRE GAGES FUSE ECM SERVICE ENGINE SOON LIGHT CONTROL DRIVER IGN 12 V A5 S.E.S LAMP A BRAKE SWITCH B AUTOMATIC TRANSMISSION TCC SOLENOID A B TCC CONTROL A/T A7 c rn D I I FIEJDCIBIA EGR SOLENOID EGR CONTROL A4 & d CANISTER PURGE SOLENOID CANSITER PURGE A3 (GRAY CONN.) c2 AIR CONTROL SOL DIVERT SOLENOID P (BLACK CONN.) AIR SWITCH SOLENOID PORT SOLENOID - A2 I , FIEIDCIBIA I I , FAN CONTROL RELAY E B+ - D - FAN B+ C - FUSE COOLING FAN CONTROL c1 B A COOLING \ - ECM I FAN ECM DIAGNOSTIC TEST SERIAL DATA SYSTEM GROUND SYSTEM GROUND SYSTEM GROUND COOLING FAN REQUEST, HIGH A/C PRESSURE MAT SIGNAL V REFERENCE TPS SIGNAL 5V RETURN COOLANT TEMP SENSOR SIGNAL 5.0LITRE ECM FUSE & HOLDER - -I 12 VOLT 12 VOLT FUEL PUMP RELAY DRIVER ( + 12 VOLT) A1 SYSTEM GROUND A12 PUMP FUEL PUMP VOLTAGE MONITOR I MAF SENSOR POWER R E L T SYSTEM GROUND ~1 ANALOG GROUND ~ 1 MAF SIGNAL BURN-OFF CONTROL - I ENGINE GROUND FUEL iA , B -C - OIL PRESSURE SWITCH E MAF SENSOR BURN-OFF RE LAY A must book technician or This book will take you from easily understoodI basic electrical theory t6 microcomputer engine control A concept in automotive technology is explained It will introduce you to the new techniques and took which will enable you to diagnose and fix today's automobiles rE-~.s ,=, the veer, r C + a v t r a r n m h WDII ~ w r ~ m n " '-5 - Brock Yates Car & Driver Magazine' - L - f i r , + !! ! -M*r I.: , You will learn how to: Use Ohm's Law for diagnosis Determine electical failures Access ECM codes Use swners reliably ~se~wiring harness adapters to pinpoint open & short c i r ~ i t s t-xTMs - ook is for: for your audi improve and profession IGUIII rrrurr -* + L-4 , I ?u , What n t h m r e a r m e a v i n m m :A UWI;W~U I W I # ; % -_ - a Dr Dawn Lee ~ e f i e l d Texas A&M University r:" t ") -4 - Definitelythe best available text onthe -subject for my students ': -1 - AuWmtW Enthysiasts AutomatSve Technology Students ProfessionalAutomotive Technicians If Rick Maldonado v! Alief-Hastings High School,H w , T& - + This book is your reference on GM-andBosch technology Electrical & electronic sensors, wiring, ECM operation, diagnostic procedures and : $ proper repair procedures are explained C, , - ,:- Written by a former GM instructor who has taught over 7,000 professional techjcians This stepby-step guide is quick to read and easv to a~ohr L p m 24 C$4 - ,