1988 PONTIAC FIERO diagram

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

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

BRlVEABlLlTY AND EMISSIONS 2.8L (VIN 5) 6E3-A-3
ENGINE GND'S BACK VIEW
OF
CONNECT OR
TO VSS BUFFER
OXYGEN SENSOR
ENGINE GND.
MANIFOLD AIR
TEMPERATURE
4 WAY INJ.
JPR. CONN.
7-14-87
Figure A1-2 -Wiring Diagram 2.8L "F" Series (1 of 3)

DRIVEABILITY AND EMISSIONS 2.8L (VIN S) 6E3-A-5
ECM
BRAKE SWITC
BACK
VIEW OF
AIR DIVERT SOLENOID
MANUALITRANS
IGNITION 12V
TANMIHT 250 ALTERNATOR
Figure A1-4 - Wiring Diagram 2.8L "F" Series (3 of 3)

6E3-A-"I 2.8L (VlN S) DRIVEABILITY AND EMlSSlONS
TO OIL PRESS. SW.
&FUEL PUMP RELAY
FUSE
81 HOLDER BATTERY 12 V .. m.. . n.
. . . . . . . . FUSIBLE LINK
439 PNWBLK
419 BRNNVHT
SERIAL
DATA
451
WHTJBLK
450 BLKNVHT
ALDL CONNECTOR
NO "SERVICE ENGlNE SOON" "LIGHT
2.8b (VIM 5) 'T" "SERIES (PORT)
Circuit Description:
There should always be a steady "Service Engine Soon" light when the ignition is "ON" and engine stopped.
Battery is supplied directly to the light bulb. The electronic control module
(ECNI) will control the light and
turn it "ON" by providing a ground path through CKT 419 to the ECM.
Test Description: Numbers below refer to circled
numbers on the diagnostic chart.
1. If the fuse in holder is blown refer to facing page of
Code
54 for complete circuit.
2. Using a test light connected to 12 volts probe each
of the system ground circuits to be sure a good
ground is present. See ECM terminal end view in
front of this section for
ECM pin locations of
ground circuits.
Diagnostic Aids:
Engine runs OK, check:
@ Faulty light bulb.
@ CKT 419 open.
@ Gage fuse blown.
This will result in no oil or
generator lights, seat belt reminder, etc. Engine
cranks but will not run.
@ Continuous battery - fuse or fusible link open.
@ ECM ignition fuse open.
@ Battery CKT 340 to ECM open.
@ Ignition CKT 439 to ECM open.
e Poor connection to ECM.
Solenoids and relays are turned "ON"
and "OFF"
by the ECM, using internal electronic switches called
"drivers". Each driver is part of a group of four called
"Quad-Drivers". Failure of one driver can damage
any other driver in the set. Solenoid and relay coil
resistance must measure more than 20 ohms. Less
resistance will cause early failure of the ECM
"driver".
Before replacing ECM, be sure to check the coil
resistance of all solenoids and relays controlled by the
ECM. See ECM wiring diagram for the
solenoid(s)
and relay(s) and the coil terminal identification.

6E3-A-36 2.8L (VlN 5) DRIVEABILIW YW EMISSIONS
- PARK OR NEUTRAL
CODE 24
VEHICLE SPEED SENSOR (VSS) CIRCUIT
2.8L (VIN 5) ""FYMIES (PORT)
Circuit Description:
The ECM applies and monitors 12 volts on CKT 437. CKT 437 connects to the vehicle speed sensor buffer
which alternately grounds CKT
437 when drive wheels are turning. This pulsing action takes place about 2000
times per mile and the ECM will calculate vehicle speed based on the time between "pulses".
A "SCAN" tool reading should closely match with speedometer reading with drive wheels turning.
Test Description: Numbers below refer to circled
numbers on the diagnostic chart.
1. Code
24 will set if:
@ CKT 437 voltage is constant.
@ Engine speed between 1400 and 3600 rpm.
o Less than 2% throttle opening.
Low load condition (low air flow).
@ Not in park or neutral.
e All conditions must be met for 3 seconds.
These conditions are met during a road load
deceleration.
2. A voltage of less than 1 volt at the 15-way
connector indicates that the CKT
437 wire may be
shorted to ground. Disconnect CKT
437 at the
VSS buffer.
If voltage now reads above 10 volts,
the VSS buffer is faulty. If
voltage remains less than
10 volt, then CKT 437
wire is grounded or open. If 437 is not grounded or
open,
check for a faulty ECM connector or ECM.
Diagnostic Aids:
If "Scan" displays vehicle speed, check
paruneutral switch CHART C-1A on vehicle with
auto trans.
If switch is OK, check for intermittent
connections. An open or short to ground in CKT
437
will result in a Code 24. If the customer also
complained about
a loss of mph on the I.P., check the
P.M. generator circuit. Refer to Section "8A" for
complete wiring diagram.
Refer to "Intermittents" in Section
"B".