1988 PONTIAC FIERO check engine light

6E2-C1-14 DRlVEABlLlTV AND EMISSIONS - 5.OL (VIN E)
806 PPUWHT CRANK SIGNAL
STARTER SOLENOID
('HOT' DURING CRANK)
CHART C-l B
CRANK SIGNAL
5.OL (VIN E) "F" "SERIES (TBI)
Circuit Description:
Crank signal is a 12 volts signal to the ECM during cranking to allow enrichment and cancel diagnostics
until engine is running and 12 volts is no longer on circuit.
Test Description: Numbers below refer to circled 2. Checks to determine if source of blown fuse was a
numbers on the diagnostic chart. faulty
ECM.
1. Checks for normal (cranking) voltage to terminal
"C9" of ECM. Test light should be "ON" during
cranking.

DRIVEABILITY AND EMISSIONS - 5.0b (VIN E) 6E2-C9-15
RECHECK FUSE.
CLEAR CODES AND CONFIRM "CLOSED LOOP" OPERATION AND NO "SERVICE
ENGINE SOON" LIGHT.

6E2-CZ-16 DRIVEABILITY AND EMISSIONS - 5.OL (WIN E)
CHART C-2C
IDLE AIR CONTROL (IAC) VALVE CHECK
5.OL (VIN E) "F'" SERIES (TBI)
Circuit Description:
The ECM controls idle rprn with the IAC valve. To increase idle rpm, the ECM moves the IAC valve out,
allowing more air to pass by the throttle plate. To decrease rpm, it moves the IAC valve in, reducing air flow by
the throttle plate. A "Scan" tool will read the
ECM commands to the IAC valve in counts.
The higher the
counts, the more air allowed (higher idle). The lower the counts, the less air allowed (lower idle).
Test Description: Numbers below refer to circled
numbers on the diagnostic chart.
1. Continue with test, even if engine will not idle. If
idle is to low, "Scan" will display 80 or more
counts, or steps. If idle is high, it will display
"0"
counts. Occasionally, an erratic or unstable idle
may occur.
Engine speed may vary 200 rpm, or
more, up and down. Disconnect IAC. If the
condition is unchanged, the IAC is not at fault.
2. When the engine was stopped, the IAC Valve
retracted (more air) to a fixed "Park" position for
increased air flow and idle speed during the next
engine start. A "Scan" will display 100 or more
counts. When performing this test, immediately
note rprn on start up, because, on a warm engine,
the rprn will decrease rapidly.
3. Be sure to disconnect the IAC valve prior to this
test.
The test light will confirm the ECM signals
by
a steady or flashing light on all circuits.
4. There is a remote possibility that one of the
CKTs
is shorted to voltage, which would have been
indicated by a steady light. Disconnect ECM and
turn the ignition
"ON" and probe terminals to
check for this condition.
Diagnostic Aids:
A slow unstable idle may be caused by a system
problem that cannot be overcome by the
IAC. "Scan"
counts will be above 60 counts, if too low,
and "0"
counts, if engine speed is too high.
If idle is too high, stop engine. Ignition "Oh'".
Ground diagnostic terminal. Wait 30 seconds for
IAC to seat, then, disconnect IAC. Lnground
diagnostic terminal and start engine. If idle speed is
above 450 rprn in drive, locate and correct vacuum
leak. If rpm is less than 450 rpm,
ad,jrlst minimum
idle speed, or correct other conditions, which may
affect idle. refer to Rough Unstable or Incorrect Idle,
in Symptoms, Section
"R".
@ System too lean (Hi.gh AirJFuel Ratio)
Idle speed may be too high or too low. Engine
speed may vary up and down, disconnecting IAC
does not help. May set Code
33.
"Scan" and/or Voltmeter will read an oxygen
sensor output less than 300 mv
(.3 volts). Check
for low regulated fuel pressure or water in
fuel. A
lean exhaust, with an oxygen sensor outpirt fixed
above 800
mv (.8 volts), will be a contaminated
sensor, usually silicone. This may also set
a Code
45.
@ System too rich (Low AirIFuel Ratio)
Idle speed too low. "Scan" counts usually above
80. System obviously rich and may exhibit black
srnoke exhaust.
"Scan" tool and/or Voltmeter will
read an oxygen
sensor signal fixed above 800
mv (.8 volts).
Check:
- High fuel pressure
- Injector leaking or sticking
@ Throttle Body. Remove IAC and inspect bore for
foreign material or evidence of
IAC valve
dragging the bore.
@ If above ;
e all OK, refer to "Rough, Unstable,
Incorrect Idle or Stalling", in Symptoms, Section
"I<".

CHART C-5
ELECTRONIC SPARK CONTROL (ESC) SYSTEM CHECK
(ENGINE KNOCK, POOR PERFORMANCE, OR POOR ECONOMV)
5.OL (VIN E) "F" SERIES (TBI)
Circuit Description:
Electronic spark control is accomplished with a module that sends a voltage signal to the ECM. As the
knock sensor detects engine knock, the voltage from the ESC module to the ECM is shut "OFF" and this
signals the ECM to retard timing, if engine rpm is over about 900.
Test Description: Numbers below refer to circled
numbers on the diagnostic chart.
1. If a Code
43 is not set, but a knock signal is
indicated while running at 1500 rpm, listen for an
internal engine noise. Under a no load condition,
there should not be any detonation, and if knock is
indicated, an internal engine problem may exist.
2. Usually a knock signal can be generated by tapping
on the right exhaust manifold. This test can also be
performed at idle. Test number 1 was run at 1500
rpm, to determine if a constant knock signal was
present, which would affect engine performance.
3. This tests whether the knock signal is due to the
sensor, a basic engine problem, or the ESC module.
4. If the module ground circuit is faulty, the ESC
module will not function correctly. The test light
should light indicating the ground circuit is OK.
5. Contacting CKT 496, with a test light to 12 volts,
should generate a knock signal to determine
whether the knock sensor is faulty, or the ESC
module can't recognize a knock signal.
Diagnostic Aids:
If the ESC system checks OK, but detonation is the
complaint, refer to
Detonation1 Spark knock in Section
"B".

DRIVEABILIW AND EMISSIONS 5.OL (VIN E) 6E2-C5-5
THIS CHART SHOULD BE USED AFTER ALL OTHER CAUSES OF SPARK KNOCK HAVE BEEN CHECKED. I.E., TIMING. EGR, ENGINE
TEMPERATURE OR EXCESSIVE ENGINE NOISE,ETC. IF CODE 43 IS SET, USE THAT CHART FIRST.
@ PROBE HARNESS TERMINAL "D" (CKT 486) EVlEW "DIAGNOSTIC
WITH A TEST LIGHT TO 12 V.
IDS" ON FACING PAGE

6EZ-C6-2 5.OL (VIN E) DRIVEABILITY AND EMISSIONS
Air enters the body of the valve from the pump.
Air pressure builds against the control valve and for:
@ Cold Mode - The port solenoid is energized
which in turn opens the port valve and allows
flow to the exhaust ports.
@ Warm Mode - The port solenoid is de-
energized and the converter solenoid
energized which closes the port valve and
keeps the converter valve seated, thus forcing
flow past the converter valve and to the
converter.
@ Divert Mode - Both solenoids are de-energized
which opens the converter valve, allowing air
to take the path of least resistance,
i.e., out the
divert
/ relief tube to atmosphere.
TO CONVERTER AIR INLET
1 TO EXHAUST PORTS 1 SOLENOID / RELIEF + DIVERT AIR 45 0506-6E
Figure C6-2 - A.I.R. System Control Valve
Air is diverted to the atmosphere under the
following conditions:
@ Rich operation.
@ When the ECM recognizes a problem and sets the
"Service Engine Soon" light.
@ During deceleration.
During high RPM operation when air pressure is
greater than the setting for the internal relief
valve.
RESULTS OF lNCORRECP OPERATION
If no air (oxygen) flow enters the exhaust stream
at the exhaust ports, HC and CO emission levels will
be too high.
Air flowing to the exhaust ports at all times could
increase temperature of the converter.
Air flowing at all times to the catalytic converter
may cause converter overheating during rich
operation. Electrical failure
(open circuit) of the control valve
will divert air flow overboard at all times. Air will
flow to the converter at all times if an open circuit
occurs to the switching valve (converter solenoid).
Mechanical failures in the valves could cause the
air to flow incorrectly to the exhaust ports or the
converter.
DIAGNOSIS
The diagnosis of the AIR system is covered in
CHART C-6 at the end of this section.
OPERATIONAL CHECKS
Air Pump
The air pump is a positive displacement vane type
which is permanently lubricated and requires no
periodic maintenance.
Accelerate engine to approximately
1500 rpm's
and observe air flow from
hose(s). If air flow increases
as engine is accelerated, pump is operating
satisfactorily. If air flow does not increase or is not
present, proceed as follows:
a Inspect
1. For proper drive belt tension.
2. For a leaky pressure relief valve. Air may be
heard leaking with the pump running.
NOTICE: If the engine or underhood compartment is
to be cleaned with steam or high-pressure
detergent, the centrifugal filter fan should
be masked off to prevent liquids from
entering the pump (see Fig.
C6B-3).
NOTICE: The AIR System is not completely
noiseless. Under normal conditions, noise
rises in pitch as engine speed increases.
inspect
3. For a seized Air Injection Pump.
3. Hoses, tubes and all connections for leaks and
proper routing.
5. For air flow from control/switching valve.
6. AIR injection pump for proper mounting and bolt
torque.
7. If no irregularities exist and the AIR injection
pump noise is still excessive, remove and replace
pump.

6E2-C6-6 DRIVEABILITY AND EMISSIONS - 5.OL (VIN E)
A.I.W. CONVERTER SOL.
CONNECTORS
429 BLWPNK
CONNECTOR CONNECTOR
CHART C-6
AIR MAMAGEMENKHECM - PEDES VALVE
(PRESSURE OPERATED ELECTRlC DIVERVELECTRIC SWITCHING)
5.Qb (VIN E) ""FYSERIES (TBI)
Circuit Description:
Air management is controlled by a port valve and a converter valve, each with an ECM controlled vacuum
solenoid. When the solenoid is grounded by the ECM,
AIR pressure will activate the valve and allow pump air
to be directed as follows:
Neither solenoid grounded by the
ECM - Air pump air diverted to atmosphere. Converter solenoid grounded
by the
ECIM - Air pump air to converter.
Port solenoid grounded by the ECM
- Air pump air to exhaust ports.
Test Description: Numbers below refer to circled
numbers on the diagnostic chart.
I. This is a system functional check. Air is directed
to ports during "Open Loop" and all engine start in
"Open Loop" even on a warm engine. Since the air
to the ports time is very short on some engines,
prepare to observe port air prior to engine start up.
On some engines, this can be done by squeezing a
hose. On others, steel pipes have
to be
disconnected.
2. This should normally set a Code 22. When any
code is set, the
ECM opens the ground to the air
control valve and allows air to divert. This checks
for
ECM response to a fault. A ground in the
control valve circuit to the ECM would prevent
divert action.
3. This checks for a grounded circuit to the ECM.
Test light
"OFF" is normal and would indicate the
circuit
is not grounded.
4. Checks for an open in the solenoid control circuits.
Grounding the test terminal should ground both
solenoid circuits. Normally, the test light should
be "ON" which indicates the problem is not in the
ECM or wiring but at the solenoid connections or
valve itself.
5. Checks for a grounded switching valve circuit.
Test light "OFF" would indicate the circuit is
normal and fault is in the valve.

SECTION PAGE
A
Acceleration Mode .................... C2-2
AIC Request Signal
General Description
................. C1-4
Diagnosis ......................... C1-5
Air Injection Check Valve C6-3
Air Injection Control (Pedes) Valve
........ C6-3
Air
lnjection Reaction (A.I.R.) System
General Description
.................. C6- 1
Diagnosis ......................... C6-2
Part Information
.................... C6-4
Air Management Check (Pedes)
.......... C6-6
Air Pump
............................ C6-2
........................... Service C6-3
ALDL Connector ....................... A-1 2
Automatic Transmission Converter Clutch
(TCC) Electrical Diagnosis
.............. C8-4
C8-6
B
Backfire ............................ 6-6
......... Battery Voltage Correction Mode C2-2
Before
Start~ng ...................... B-1
C
Cal Pak General
Descript~on ................. C1-2
Service
........................... C1-8
Canister Control Valve
................. C3-2
Canister Hoses
....................... C3-3
Canister Purge Solenoid
................ C3-3
Canister Purge Valve Check
............. C3-6
Chart A-
I :
No Service Engine Soon Light .......... A-10
Chart A-2:
No ALDL Data. Or Won't Flash Code 12.
Or Service Engine Soon Light On Steady
. . A-1 2
Chart A-3:
Engine Cranks But Won't Run
.......... A-14
Chart A-7:
Fuel System Diagnosis
................ A-1 8
Chart
B-1:
Restricted Exhaust System Check ........ 6-7
Chart C-IA:
ParkINeutral Switch Diagnosis ......... Cl-12
Chart C-16:
Crank Signal
....................... C1-14
Chart C-1 D
.................. MAP Output Check C1-16
SECTION
Chart C-2C:
Idle Air Control (IAC) System Check ...... C2-18
Chart C-3:
Canister Purge Valve Check
........... C3-6
Chart C-4B:
Ignition System Check
................ C4-4
Chart C-5:
Electronic Spark Control
(ESC) .......... C5-4
Chart C-66:
Air Management Check
.............. C6-6
Chart C-7:
Exhaust Gas Recirculation
............. C7-4
Chart
C-$A:
Transmission Converter Clutch (TCC) .... C8-4
Chart
C-8A
700-4R Transmission Electrical Diagnosis . . C8-6
Chart
C-86:
Shift Light ......................... C8-8
Chuggle
............................ B-3
Clear Flood Mode
..................... C2-2
Closed Loop
......................... C2-2
Code12
............................ C4-2
Code13
............................ A-22
Code14
............................ A-24
Code43
............................ A-42
Code44
............................ A-44
Code45
............................ A-46
Code54
............................ A-48
Codes 5 1.52. 55
...................... A-50
Component Location
.................. A-2
Control Valves
....................... C3-3
Coolant Temperature Sensor
General Description
.................. C1-2
Diagnosis
.......................... Cl-5
Service
........................... C1-8
Cuts Out ............................ 6-4
Crank Signal General Description
................. C1-4
Diagnosis
......................... C1-14
D
Deceleration Mode .................... C2-2