1988 PONTIAC FIERO light

INDEX
SECTION PACE
....................... Detonation... B-4
.................. Diagnostic Procedure 2-5
................ Diagnostic Circuit Check A-8
..................... Dieseling. Run On B-6
Distributor Reference Signal
................. General Description C1-4
......................... Diagnosis C1-5
E
.................... ECM Terminals ... A-6
.................. ECM Wiring Diagram A3-A6
..................... EGR Control Valve C7-1
................. Valve Identification C7-2
................... Diagnosis. Service C7-2
EGR Control Solenoid
.................. C7-3
Parts Information
................... C7-3
......................... EGR Check C7-4
Electronic Control Module
................. General Description C1-I
......................... Diagnosis C1-5
............................ Service C1-6
..................... Function Check C1-6
Electronic Spark Control (ESC) System
................. General Description C5-1
................... Diagnosis. Service C5-I
Engine Coolant Temperature Sensor
................. General Description C1-2
......................... Diagnosis C1-5
Engine Cranks But Won't Run
............ A-14
........................ Engine Knock C5-4
.......................... ESC Module C5-1
.......................... ESC Sensor C5-1
..................... ESC System Check C5-4
ESTIlgnition System ................... C4-1
Evaporative Emission
Conirol System
General Description
................. C3-1
.......................... Diagnosis C3-2
Exhaust Emissions Excessive (Odors)
....... B-7
Exhaust Gas Recirculation (EGR) System
..... C7-1
Exhaust System Check Restricted
......... B-8
Fuel Control System
General Description
................. C2-1
Diagnosis. Parts Information
........... C2-6
Fuel Cutoff Mode
.................... C2-2
Fuel Meter Body Assembly
.............. C2- 1 I
Fuel Injectors ........................ C2-3
Fuel Meter Cover Assembly
.............. C2-8
Fuel Pressure Connection Assy
............ C2- 10
SECTION PAGE
........... Fuel Pressure Relief Procedure C2-6
.............. Fuel Pump Electrical Circuit C2-5
...................... Fuel Pump Relay C2-15
.................. Fuel System Diagnosis A- 18
............... Fuel System Pressure Test C2-7
......... Fuel Tank Pressure Control Valve C3-3
................... Fuel
Vapor Canister C3-3
G
.................. General Information 2-5
H
.......................... Hard Start B-2
.......... HE1 High Energy Ignition System C4-1
.......................... Hesitation
B-4
............ ldle Air Control System Check
.................. ldle Air Control Valve
......................... Diagnosis
....................... Service (EST)
Ignition System
................. General Descr~ption
......................... Diagnosis
Check
............................
........................ Incorrect ldle
.................. lnformation Sensors
................... Injector Balance Test
........................ Intermittents
......................... Introduction
Knock Sensor
................. General Description C1-4
......................... Diagnosis C1-6
....................... Lack Of Power B-3
Light. Manual Transmission Shift
......... C8-8
Light. Service Engine Soon
.............. A-10
Manual Transmission Electrical Diagnosis
... C8-10
Manual Transmission Overdrive Relay ..... C8-3
MAP Sensor
General Description
................. C1-2

INDEX
SECT ION PAGE
Diagnosis ......................... C1.5. 16
Service
........................... C1-8
MAT Sensor
General Description
.................. C1-2
Diagnosis
......................... C1-5
Service
........................... C1-7
Minimum
Idle Speed Adjustment ......... C2-14
Misses
.............................. B-4
Negative Backpressure Valve
............ C7-1
Non-Adjustable TPS Output Check
........ C2-14
Oil Pressure Switch
.................... C2-16
Oxygen Sensor
(02)
General Description ................. C1-3
Diagnosis ......................... C1-5
Service
........................... C1-9
Open Loop
.......................... C2-2
Park Neutral Switch
General Description
................. C1-4
Diagnosis
.......................... C1-5
C1-12
Service. Parts Information
............. C1-9
Poor Fuel Economy
.................... B.5.
C5- 1
Poor Performance
.................... C5-1
Positive Crankcase Ventilation (PCV)
General Description. Diagnosis
......... C13-1
Service. Parts Information
............. C13-2
Pressure Regulator
.................... C2-3
PROM General Description
................. C1-1
Diagnosis ......................... C1-5
Service
........................... C1-6
....................... Quad Drivers. C1-4
Reference Signal
...................... C1-5
Rough
Idle .......................... B-5
RunMode ........................... C2-2
SECTION PAGE
S
Sag ................................ B-4
"Scan" Data
......................... A-8
Sensor Information
.................... C1-2-9
Setting Timing
....................... C4-2
Shift Light
........................... C8-8
Sluggish
............................ B-3
Spark Knock
......................... B-4
Spongy
............................. 8-3
Stalling ............................. B-5
Starting Mode
........................ C2-1
Stumble
............................ B-4
Surges
............................. B-3
Table Of Contents
.................... A-1
Tank Pressure Control Valve
General Description
................. C3-2
Diagnosis
......................... C3-3
Throttle Body Injection Unit
General Description
................. C2-3
Service
........................... C2-7
C2- 14
Throttle Position Sensor
................ C2-5
General Description
................. C1-3
Diagnosis
......................... C1-5
Service
........................... C1-9
C2- 12
Transmission Converter Clutch TCC System
General Description
................. C8-1
Diagnosis
......................... C8-2
C8-4 C8-6
Parts Information
................... C8-2
Unstable
Idle ........................ B-5
....................... Vapor Canister C3-1
Vehicle Speed Sensor (VSS)
.................. General Description C1-4
Diagnosis
......................... 4.5
..................... Wiring Diagrams 8-3

DRIVEABILITY AND EMISSIONS 2.8L (VIN 5). 5.OL (VIN F) & 5.7L (VIN 8) 6E3-1
SECTION 6E3
TY AND EM
THIS SEC"T0N APPLIES TO:
2.8L LB8 (VlN S) "F" SERIES
5.OL LB9 (VIN F ) "F'" SERIES
5.7L L98 (VIN 8) ""F3"lES
CONTENTS
INTRODUCTION
2.8L (VIN 5). 5.OL (VIN F) & 5.7L (WIN 8)
General Description ................... 8
Diagnosis Procedure ................... 8
SECTION A . DIAGNOSTIC CHARTS
2.8L (VIN S)
Table of Contents .................... A-1
Engine Components and Wiring
Component Locations
............... A-2
Wiring Diagrams (1 of 3) ............. A.3.4. 5
ECM Terminal End View .............. A-6
Diagnostic Circuit Check ................ A-8
No "Service Engine Soon" Light
Chart A-I
......................... A-10
No ALDL Data . "Service Engine Soon"
Light "ON" Steady (Won't Flash Code 12)
Chart A-2
......................... A-12
Engine Cranks But Won't
.... Chart A-3 (1 of 2)
Fuel System Diagnosis Run ................ A-14
. ChartA-7(1 of
2) ................... A-18
Cold Start Valve
Chart A-9
......................... 8-22
. .... Code 13 Oxygen Sensor Circuit (Open) A-24
Code 14 . Coolant Temperature Sensor Circuit
. (High Temp Indicated) .............. A-26
Code 15 . Coolant Temperature Sensor Circuit
(Low Temp
. Indicated) .............. A-28
Code 2 1 . Throttle Position Sensor (TPS) Circuit
(Signal Voltage High)
........ , ...... A-30
Code 22 . Throttle Position Sensor (TPS) Circuit
(Signal Voltage Low)
......... , ...... A-32
Code 23 . Manifold Air Temperature (MAT) Sensor
. Circuit (Low Temp Indicated) .......... A-34
Code 24 . Vehicle Speed Sensor
(VSS) Circuit ....................... A-36
Code 25 . Manifold Air Temperature (MAT)
Sensor Circuit (High Temp
. Indicated) .... A-38
Code 32 . EGRSystem Failure ............ A-40
Code 33 . Mass Air Flow (MAF) Sensor Circuit
(GMISEC High) .................... A-42
Code 34 . Mass Air Flow (MAF) Sensor Circuit
(GMISEC Low) .................... A-44
Code 41 . Cylinder Select Error ........... A-46
Code 42 . Electronic Spark Timing Fault .... A-48
Code 44 . Oxygen Sensor Circuit
(Lean Exhaust Indicated)
............. A-50
Code 45 . Oxygen Sensor Circuit
(Rich Exhaust Indicated)
.............. A-52
Code 54 . Fuel Pump Circuit (Lowvoltage) . . A-54
Code 5 1 . PROM Error
(Faulty or Incorrect PROM)
............ A-56
Code 52 . CALPAK Error
(Faulty or Incorrect CALPAK)
.......... A-56
Code 53 . System Over Voltage ........... A-56
Code 55 . ECM Error ................... A-56
SECTION B . SYMPTOMS
2.8L (WIN 5)
Table of Contents .................... B-1
Before Starting ...................... B-1
Intermittents ........................ B-2
Hard Start .......................... 8-2
Hesitation. Sag. Stumble ............... 8-3
Surges and/or Chuggle ................. 8-3
Lack of Power. Sluggish. or Spongy ........ B-4
DetonationJSpark Knock ............... 6-4
Cuts Out. Misses ...................... 8-5
Backfire ............................ 8-5
Poor Fuel Economy .................... B-6
Dieseling. Run.On ..................... 8-6
Rough. Unstable. or lncorrect Idle. Stalling . . €3-6
Excess~ve Exhaust Emissions or Odors ...... 8-7
Restr~cted Exhaust System Check
Chart
B-I ......................... 8-63

6E3-4 2.8L (VIN S) . 5.OL (VIN F) & 5.7L (VIN 8) DRIVEABILITY AND EMISSIONS
ON-CAR SERVICE ..................... C7-3
EGRVALVE
........................ C7-3
EGR Manifold Passage
............... C7-3
EGR Manifold Passage
............... C7-4
ELECTRONIC VACUUM REGULATOR
VALVE
.......................... C7-4
EVRV FILTER REPLACEMENT
.......... C7-4
PARTS INFORMATION
................. C7-4
Exhaust Gas Recirculation Check
Chart C-7
......................... C7-6
SECTION
C8 . 2.8L (VIN S)
TRANSMISISON CONVERTER CLUTCH (TCC) SYSTEM
AND MANUAL TRANSMISSION SHIFT LIGHT
GENERAL DESCRIPTION
................ C8-1
PURPOSE ......................... C8-1
OPERATION ....................... C8-1
DIAGNOSIS
......................... C8-1
SHIFT LIGHT (M/T) DESCRIPTION ........ C8-1
DIAGNOSIS
......................... C8-1
ON-CAR SERVICE ..................... C8-1
Automatic Transmission
Converter Clutch (TCC)
. (1 of 2)
Chart C-8
......................... C8-2
Transmission Converter Clutch
(TCC) Electrical Diagnosis
. (2 of 2)
Chart C-8
......................... C8-4
SECTION C10 . 2.8L (WIN S)
ECM CONTROLLED AIR CONDITIONING
GENERAL DESCRIPTION
................ C10-1
OPERATION ....................... C10-1
DIAGNOSIS ......................... C10-1
ON-CARSERVICE ..................... C10-1
FJC Clutch Control
Chart C-
1 0 ........................ C10-2
SECTION C12 . 2.8L (VlN S)
COOLING FAN CONTROL
GENERAL DESCRIPTION
................ C12-1
OPERATION ....................... C12-1
DIAGNOSIS
......................... C12-1
PARTS INFORMATION ................. C12-1
Cooling Fan Control Circuit (1 of 2)
Chart
C- 12 ........................ C12-2
Cooling Fan Control Circuit (2 of 2)
Chart C-12
........................ C12-4
SECTION C13
. 2.8L (WIN S)
POSITIVE CRANKCASE VENTILATION (PCV)
GENERAL DESCRIPTION
................ C13-1
RESULTS OF INCORRECT OPERATION
.... C13-1
DIAGNOSIS
......................... C13-1
FUNCTIONALCHECK OF PCV VALVE .... C13-1
ON-CAR SERVICE
..................... C13-2
PARTS INFORMATION
................. C13-2
SEC"T0N A . DIAGNOSTIC CHARTS
5.OL (VIN F) & 5.7L (VIN 8)
.................... Table of Contents A-1
Engine Components and Wiring
............... Component Locations A-2
Wiring Diagrams
(1 of 4) ............. A-3
ECM Terminal End View
.............. A-7
Diagnostic Circuit Check
................ A-8
No "Service Engine Soon" Light
......................... Chart A-1 A-10
No ALDL Data
. "Service Engine Soon"
Light "ON" Steady (Won't Flash Code 12)
Chart A-2
......................... A-12
Eng~ne Cranks But Won't Run
Chart A-3
(1 of 2) ................... A-14
Fuel System
Diagnos~s
Chart A-7 (1 of 2) ................... A-18
Cold Start Valve
Chart A-9
......................... A-22
Code 13
. Oxygen Sensor Circuit (Open) .... A-24
Code 14
. Coolant Temperature Sensor Circuit
(High Temp
. Indicated) .............. A-26
Code
1 5 . Coolant Temperature Sensor C~rcuit
. .............. (Low Temp Ind~cated) A-28
Code 21
. Throttle Pos~tlon Sensor (TPS) Circuit
(Signal Voltage High)
............... A-30
Code 22
. Throttle Pos~t~on Sensor (TPS) Circuit
................ (Signal Voltage Low) A-32
Code 23
. Manifold Air Temperature (MAT) Sensor
C~rcuit (Low Temp . Indicated) .......... A-34
Code 24
. Vehicle Speed Sensor
....................... (VSS) Circuit A-36
Code 25
. Manifold Air Temperature (MAT)
Sensor Circuit (High Temp
. Indicated) .... A-38
. ............ Code 32 EGR System Failure A-40
Code 33
. Mass Air Flow (MAF) Sensor Circuit
.................... (GMISECHlgh) A-42
Code 34
. Mass Air Flow (MAF) Sensor Circu~t
.................... (GMISEC Low) A-44
Code 36 Mass Air Flow
(MAF) Sensor
.. ..... ........... Burn-Off Circuit , , A-46
. ........... Code 41 Cyl~nder Select Error A-48
... . Code 42 Electronic Spark Timing Circuit A-50
Code 43 Electronic Spark Control
(ESC)
C~rcuit ....................... A-52
Code 44
. Oxygen Sensor Circu~t
(Lean Exhaust lnd~cated) ............. A-54
Code 45
. Oxygen Sensor Circuit
(Rich Exhaust Indicated)
.............. A-56
Code 54
. Fuel Pump C~rcuit (Lowvoltage) . . 14-58
. ................... Code 51 MEM-CAL A-60
Code 52
. CALPAK Error
.......... (Faulty or Incorrect CALPAK) A-60
. ........... Code 53 System Over Voltage A-60

DRIVEABILITVAND EMISSIONS Z.$L (VIN 5). 5.OL (VIN F) & 5.7L (VIN 8) 6E3-5
SECTION B . SYMPTOMS
5.OL (VIN F) & 5.7L (VIN 8)
.................... Table of Contents B-1
................... Before Starting ... B-1
. lntermittents .................... ... B-2
Hardstart .......................... B-2
............... Hesitation. Sag. Stumble 8-3
Surges andlor Chuggle ................. B-3
........ Lack of Power. Sluggish. or Spongy 8-4
DetonationISpark Knock ............... B-4
...................... Cuts Out. Misses €3-5
Backfire ............................ B-5
Poor Fuel Economy .................... B-6
Dieseling. Run.On ..................... 8-6
Rough. Unstable. or Incorrect Idle. Stalling . . B-6
Excessive Exhaust Emissions or Odors ...... B-7
Restricted Exhaust System Check
Chart
B-1 ......................... B-8
FUNCTIONAL CHECKS1
DIAGNO%"FIC CHARTS
5.OL (VIN F) & 5.7L (WIN 8)
ParkINeutral Switch
. Chart C-1A .................... ... C1-10
Injector Balance Test
Chart C-2A
........................ C2-18
Idle Air Control
Chart C-2C
........................ C2-20
Canister Purge Valve Check
Chart C-3
......................... C3-4
Ignition System Check
ChartC-4
......................... C4-4
Electronic Spark Control System Check
Chart C-5
......................... C5-4
AIR Management Check
Chart C-6
......................... C6-6
Exhaust Gas Recirculation (EGR) Check
Chart C-7
........................ C7-4
Automatic Transmission Converter Clutch (TCC)
Chart
6-814 ........................ C8-6
Manual Transmission Shift Light Diagnosis
Chart C-8B
........................ C8-10
Cooling Fan Control Circuit Diagnosis
Chart C- 1 2
........................ C12-2
SECTION C . COMP0NEN"I"SVSTEMS
5.OL (VIN F) & 5.7L (WIN 8)
Table of Contents .................... C-1
SECTION
C1 . 5.OL (VIN F) & 5.7L (VIN 8)
ELECTRONIC CONTROL MODULE (ECM)
81 SENSORS
GENERAL DESCRIPTION
................ C1-1
ELECTRONIC CONTROL MODULE ....... C1-1
MEM.CAL ......................... C1-1
................... ECM Function. C1-1
INFORMATION SENSORS ............. C1-2
Engine Coolant Temperature Sensor . . C1-2
..................... MAF Sensor C1-2
.................... MAT Sensor C1-2
Oxygen (Oz) Sensor ..............a. C1-3
Throttle Position Sensor ............ C1-3
.................... Knock Sensor C1-3
Vehicle Speed Sensor .............. C1-3
ParkINeutral Switch (Auto Only) ...... C1-3
.................. A/C "ON" Signal C1-4
Distributor Reference Signal ......... C1-4
DIAGNOSIS ......................... C1-4
ECM ............................. C1-4
MEM.CAL ......................... C1-4
ECM INPUTS ....................... C1-4
Coolant Temperature Sensor ........ C1-5
..................... MAF Sensor C1-5
..................... MAT Sensor C1-5
Oxygen (Oz) Sensor ............... C1-5
TPS ........................... C1-5
VSS ........................... C1-5
...................... PIN Switch C1-5
A/C Request Signal ................ C1-5
Reference Signal ................. C1-5
ON-CAR SERVICE ..................... C1-5
ELECTRONIC CONTROL MODULE ....... C1-5
ECM or MEM-CAL REPLACEMENT ....... C1-6
Functional Check ................. C1-7
COOLANTSENSOR .................. C1-7
MAF SENSOR ...................... C1-8
MAF SENSOR POWER & BURN-OFF RELAY . C1-8
OXYGEN SENSOR .................. C1-8
THROTTLE POSITION SENSOR ......... C1-8
PARKINEUTRAL SWITCH ............. C1-9
................. PARTS INFORMATION C1-9
ParkINeutral Switch
Chart
C-1 ..................... ... C1-10
SECTION C2 . 5.0L (WIN F) & 5.7L (WIN 8)
FUEL CONTROL SYSTEM
................ GENERAL DESCRIPTION C2-1
......................... PURPOSE C2-1
.............. MODES OF OPERATION CZ-2
................... Starting Mode C2-2
Clear Flood Mode ................. CZ-2
....................... Run Mode CZ-2
................ Acceleration Mode C2-2
............... Decelerat~on Mode C2-3
Battery Voltage Correction Mode ..... C2-3
................. Fuel Cutoff Mode C2-3
.............. FUEL CONTROL SYSTEM C2-3
............ Basic System Operation CZ-3
................ Throttle Body Unit CZ-3
....................... Fuel Rail C2-3
.................... Fuel Injectors CZ-3
............... Pressure Regulator C2-4
....................... IAC Valve 62-4

DRIVEABILITY AND EM10010NS 2.8L (WIN S). 5.8L (VIN F) & 5.7L (VlN 8) 6E3-7
RESULTS OF INCORRECT OPERATION ..... C7-2
DIAGNOSIS
....................... C7-2
EGRVALVE ...................... 0-3
EGR Manifold Passage ............... C7-3
EGR CONTROL SOLENOID ............ C7-3
PARTS INFORMATION
................. C7-3
Exhaust Gas Recirculation Check
Chart C-7
......................... C7-4
SECTION
C8 . 5.01 (VIN F) & 5.7L (VIN 8)
TRANSMISISON CONVERTER CLUTCH (TCC) SYSTEM
AND MANUAL TRANSMISSION SHIFT LIGHT
GENERAL DESCRIPTION
................ C8-1
PURPOSE ......................... C8-1
OPERATION ....................... C8-1
DIAGNOSIS ......................... C8-1
SHIFT LlGHT(M1T) DE5CRlPTlON ........ C8-1
DIAGNOSIS ......................... C8-1
ON-CAR SERVICE
..................... C8-1
Automatic Transmission
Converter Clutch
(TCC) (1 of 2)
Chart C-8A ........................ C8-2
MIT Shift Light Check
Chart C-8B
........................ C8-6
SECTION C12 . 5.OL (WIN F) & 5.7L (WIN 8)
eoOLlNe FAN CONTROL
GENERAL DESCRIPTION ................ C12-1
OPERATION ....................... C12-1
DIAGNOSIS ................... .. .... C12-1
ON-CAR SERVICE ..................... C12-1
PARTS INFORMATION .*............... ~12-1
Cooling Fan Control Circuit (I of 2)
Chart C-12 ........................ C12-2
Cooling Fan Control Circuit (2 of 2)
Chart C- 12 ........................ C9 2 -4
SECTION C13
. 5.OL (VIN F) & 5.7L (VIN 8)
POSITIVE CRANKCASE VENTILATION (PCV)
GENERALDESCRIPTION ................ 643-1
RESULTS OF INCORRECT OPERATION .... 613-9
DIAGNOSIS ......................... C13-1
FUNCTIONAL CHECK OF PCV VALVE .... C13-4
ON-CARSERVICE ..................... C13-2
PARTS INFORMATION ................. C13-2

6E3-8 2.8L (VIM $1, 5.OL (VIN F) & 5.7L(VlN 8) BRlVEABILlTY AND EMISSIOMS
ALL NEW GENERAL MOTORS VEHICLES ARE CERTIFIED BY THE UNITED STAEES
ENVIRONMENTAL PROTECTION AGENCY AS CONFOWMlNG TO "THE REQUIREMENTS QF THE
REGULATIONS FOR THE CONTROL OF AIR POLLUTION FROM NEW MOTOR VEHICLES. THIS
CERTlFlCATlON IS CONTINGENT ON CERTAIN ADJUSTMENTS BEING SET TO FACTORY
STANDARDS. IN MOST CASES, THESE ADJUSTMENT POINTS EITHER HAVE BEEN
PERMANENTLY SEALED ANDIOR MADE
INACCESSlBLE TO PREVENT INDISCRIMINATE OR
ROUTINE ADJUSTM&M"FIN THE FIELD. FOR THIS REASON, THE FACTORY PROCEDURE FOR
TEMPORARILY REMOVING PLUGS, CAPS, ETC., FOR PURPOSES OF SERVICING THE PRODUCT,
MUST
BE STRICTLY FOLLOWED AND, WHEREVER PRACTICABLE, RETURNED TO THE
ORIGINAL INTENT QF THE DESIGN.
INTRODUCTION
GENERAL BESCRIPT18N DIAGNOSIS PROCEDURE
This section applies to engines which have a fuel
injector in the intake manifold near the intake valve
for each cylinder. It is commonly referred to as "Port
Fuel Injection".
These engines have controls to reduce exhaust
emissions, while maintaining good driveability and
fuel economy.
An engine control module
(ECM) is the heart of
this control system and has sensors used to provide
information about engine operation and the various
systems it controls. Details of basic operation,
diagnosis, functional checks, and on-vehicle service
are covered in Section "C", "Component Systems".
The ECM has the ability to do some diagnosis of
itself, and of other parts of the system. When it finds a
problem, it lights a "Service Engine Soon" light on the
instrument panel and
a trouble code will be stored in
the ECM memory. This does not mean that the engine
should be stopped right away, but that the cause of the
light coming
"ON" should be checked as soon as
reasonably possible. The
following
sections(s) are written for specific
engine applications and are clearly indentified. Be
sure to use only the section which applies to the
engine family being diagnosed.
Before using this section of the manual, you
should be familiar with the information and the
proper diagnosing procedures as described in Section
"GE". If the proper diagnosis procedures are not
followed, as described in Section
"6EM, it may result in
unnecessary replacement of good parts.
Trouble tree charts incorporate diagnosis
procedures using an ALDL "SCAN" tool where
possible.
The "SCANJ' tool has the ability to save time
in diagnosis and prevent the replacement of good
parts. The
key to using the "SCAN" tool
successfully for diagnosis lies in the technician's
ability to understand the system he is
trving to
diagnose. as well as an understanding of the
"SCAN" tool's limitations. See Section "6E" for
more information.

DRIVEABILITY AND EMISSIONS f.8b (VIN S) 6E3-A-1
Cold Oxygen Sensor
The "Diagnostic Circuit Check" verifies the On some engines.
the oxygen sensor will cool off
system is functioning correctly . some special after only a short period of operation at idle . This will
considerations to keep in mind while making the put the system into "Open Loop" . To restore "Closed
"Diagnostic Circuit Check" are: Loop"
operation. run the engine
at part throttle
several minutes and accelerate from idle to part
Blocking Drive Wheels throttle a few times .
The vehicle drive wheels should always be blocked Basic Procedure
while checking the system . If you have not reviewed the basic information on
how to
use the diagnostic procedures. go to the
introduction of this section
.
ENGINE COMPONENTS /WIRING DIAGRAMS / DIAGNOSTIC CHARTS
ComponentLocations ........................................................ PageA-2
Wiring Diagrams (1 of 3) ...................................................... Page A.3.4. 5
ECM Connector Terminal End View
.............................................. Page A-6
Diagnostic Circuit Check
...................................................... Page A-8
No "Service Engine Soon" bight
. Chart A-1 ........................................ Page A-10
No
ALBL or Won't Flash Code 12 . "Serv~ce Engine Soon" Light On Steady . Chart A-2 ........ Page A-12
. Engine Cranks But Won't Run Chart A-3 (1 of 2) .................................... Page 8-14
. Fuel System Diagnosis Chart A-7 (1 of
2) .......................................... Page A-18
Cold Start Valve
. Chart A-9 .................................................... Page A-22
Code 13 Oxygen Sensor Circuit (Open Circuit)
...................................... Page A-24
Code 14 Coolant Temperature Sensor Circuit (High Temp
. Indicated) ..................... Page A-26
Code 15 Coolant Temperature Sensor Circuit (Low Temp
. Indicated) ..................... Page A-28
Code 21 Throttle Position Sensor (TPS) Circuit (Signal Voltage High)
...................... Page A-30
Code 22 Throttle Position Sensor (TPS) Circuit (Signal Voltage Low)
...................... Page A-32
Code 23 Manifold Air Temperature (MAT) Sensor Circuit (Low Temp
. Indicated) ............ Page A-34
Code 24 Vehicle Speed Sensor (VSS) Circuit
........................................ Page A-36
Code
25 Manifold Air Temperature (MAT) Sensor Circuit (High Temp . Indicated) ............ Page A-38
Code 32
EGR System Failure .................................................... Page A-40
Code 33 Mass Air Flow (MAF) Sensor Circuit
(GMISEC High) ............................. Page A-42
Code 34 Mass Air Flow (MAF) Sensor Circuit
(GMISEC bow) ............................. Page 8-44
Code
41 Cylinder Select Error .................................................. Page A-46
Code 42 Electronic Spark Timing Fault
................... .... .................... Page 8-48
Code 44 Oxygen Sensor Circuit (Lean Exhaust Indicated)
.............................. Page A-50
Code
45 Oxygen Sensor Circuit (Rich Exhaust Indicated) ............................... Page A-52
Code 54 Fuel Pump Circuit
(Lowvoltage) .......................................... Page A-54
Code
51 PROM Error (Faulty or Incorrect PROM) ..................................... Page A-56
Code 52 CALPAK Error (Faulty or Incorrect CALPAK)
................................. Page 44-56
Code 53 System Over Voltage .................................................. Page A-56
Code55ECMError ............................O.~o.~.~e.~e~e.~e....... .. PageA-56