1988 PONTIAC FIERO light

6E2-4 5.OL (VIN E) DRIVEABILITY AND EMISSIONS
Transmission Converter Clutch (TCC)
(Electrical Diagnosis) Chart -8A
(1 of 2) ................ C8-4
700-4R Transmission
(Electrical Diagnosis) Chart -8A (2 of 2)
................ CS-6
Manual Transmission Shift Light Diagnosis
Chart C-8B
.................... CS-8
SECTION C13
POSITIVE CRANKCASE VENTILATION (PCV)
GENERAL DESCRIPTION
............... C13-1
DIAGNOSIS
......................... C13-1
RESULTS OF INCORRECT OPERATION ... C13-1
ON-CARSERVICE
.................... C13-2
PARTS INFORMATION
................. C13-2
SECTION C14
THERMOSTATIC AIR CLEANER (THERMAC)
GENERAL DESCRIPTION
............... 614-1
PURPOSE ........................ C14-1
OPERATION ...................... C14-1
DIAGNOSIS
........................ C14-2
RESULT OF INCORRECT THERMAC
OPERATION
.................... C14-2
THERMAC AIR CLEANER CHECK ........ C14-2
VACUUM MOTORCHECK ............. C14-2
TEMPERATURE SENSOR CHECK ......... C14-3
ON CAR SERVICE .................... C14-3
AIR CLEANER ELEMENT .............. C14-3
VACUUM DIAPHRAGM MOTOR ........ C14-3
SENSOR .......................... C14-3
PARTSINFORMATION ................ C14-4

DRIVEABILITY AND EMISSIONS 5.OL (VIN E) 6E2-5
ALL NEW GENERAL MOTORS VEHICLES ARE CERTIFIED BY THE UNITED STATES
ENVIRONMENTAL PROTECTION AGENCY AS CONFORMING TO THE REQUIREMENTS OF THE
REGULATIONS FOR THE CONTROL OF AIR POLLUTION FROM NEW MOTOR VEHICLES.
THlS
CERTIFICATION IS CONTINGENT ON CERTAIN ADJUSTMENTS BEING SET TO FACTORY
STANDARDS. IN MOST CASES, THESE ADJUSTMENT POINTS EITHER HAVE BEEN
PERMANENTLY SEALED
AND/OR MADE INACCESSIBLE TO PREVENT INDISCRIMINATE OR
ROUTINE ADJUSTMENT IN THE FIELD. FOR
THlS 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 OF THE DESIGN.
INTRODUCTION
GENERAL DESCRIPTION DIAGNOSIS PROCEDURE
This section applies to engines which have a fuel
injector mounted above a throttle body assembly. The
entire assembly is mounted to the intake manifold and
is referred to as "Throttle Body 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
sectionds) 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
"6E". If the proper diagnosis procedures are not
follo\l;red, as described in Section "6En, it may result in
unnecessary replacement of good parts.
Trouble tree charts incorporate diagnosis
procedures using an
ALDI, "Scan" tool, where
possible. The "Scan" 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
abilitv to understand the system
he is try in^ to
diagnose,
as well as an understanding of the
"Scan" tool's limitations. See Section
6E for more
information.

DRIVEABILITY AND EMISSIONS S.OL (VIN E) 6EZ-A-1
5.OL ENGINE
DIAGNOS"FC CIRCUIT CHECK 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
.
SECTION A
ENGINE COMPONENTS
/ WlRlNG DIAGRAMS 1 DIAGNOSTIC CHARTS
Component Locations ........................................................ Page A-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" Light. Chart A-1 ......................................... Page 14-10
No ALDL Data or Won't Flash Code 12. "Service Engine Soon" Light "ON" Steady. Chart A-2 ... Page A-I 2
Engine Cranks But Will Not Run . Chart A-3 (1 of 2) .................................. Page A-1 4
. Fuel System Diagnosis Chart A-7 (1 of 2) .......................................... Page A-1 8
Code 13 Oxygen Sensor Circuit (Open C~rcu~t) ...................................... Page A-22
Code 14 Coolant Temperature Sensor Circu~t (HighTemperature Indicated) ............... Page A-24
Code 15 Coolant Temperature Sensor Circu~t (LowTemperature Indicated) ............... Page A-26
Code 21 Throttle Position Sensor (TPS) Circu~t (S~gnal Voltage High) ...................... Page A-28
Code 22 Throttle Position Sensor (TPS) Circuit (Signal voltage Low) ..................... Page A-30
Code 23 Manifold Air Temperature (MAT) Sensor Circuit (Low Temp . Indicated) ............ Page A-32
Code 24 Vehicle Speed Sensor (VSS) Circuit ........................................ Page A-34
Code 25 Manifold Air Temperature (MAT) Sensor Circuit (High Temp . Indicated) ............ Page A-36
Code 32 Exhaust Gas Recirculation (EGR) Circuit .................................... Page A-38
Code 33 Manifold Absolute Pressure (MAP) Sensor Circuit (Signal Voltage High-Low Vacuum) . . Page A-40
Code 34 Manifold Absolute Pressure (MAP) Sensor Circuit (Signal Voltage Low-High Vacuum) . . Page A-42
Code 42 Electronic Spark Timing (EST) Circuit ...................................... Page A-44
Code 43 Electronic Spark Control (ESC) Circuit ...................................... Page A-46
Code 44 Oxygen Sensor Circuit (Lean Exhaust Indicated) .............................. Page A-48
Code 45 Oxygen Sensor Circuit (Rich Exhaust Indicated) .............................. Page A-50
Code 53 Vehicle Anti-Theft System (VATS) Circuit ................................... Page A-52
Code 54 Fuel Pump Circuit (Low Voltage) ......................................... Page A-54
Code 51 Code 51 PROM Error .................................................. Page A-56
Code 52 Calpak Error (Faulty or Incorrect Calpak) ................................... Page A-56
.......................................................... Code55ECMError PageA-56

6E2-A-2 5.OL (VIN E) DRIVEABILIW AND EMISSIONS
IFf SERIES VIN CODE: E
OCOMPUTER HARNESS
C1 Electronic Control Module
C2 ALDL diagnostic connector
C3 "SERVICE ENGINE SOON" light
C5 ECM harness grounds
C6 Fuse panel
C8 Fuel pump test connector
C9 Fuel pump fuse & ECM power
C10 Set timing connector
....,
: . ... 'NOT ECM CONNECTED
N1 Crankcase vent valve (PCV)
N4 PIS Switch
N8 Oil pressure switch
[7 CONTROLLED DEVICES 0 INFORMATION SENSORS
1 Fuel injectors A Manifold Absolute Pressure
2 Idle air control motor B Exhaust oxygen
3 Fuel pump relay
C Throttle position
5 Trans. Conv. Clutch connector
D Coolant temperature
6 EST distributor
F Vehicle speed
6a Remote ignition coil
J ESCknock
7 Electronic Spark Control module MAT (on air cleaner)
9 Air injection port solenoid
10 Air injection converter solenoid
12 Exh. Gas Recirc. vacuum solenoid
15 Fuel vapor canister solenoid
Exhaust Gas Recirculation valve
6-1
0-87
Figure A-I - Component Locations 5.OL (VIN E)

6EZ-A-10 5.0L (VIN E) DRIVEABILITY AND EMISSIONS
TO OIL PRESS. SW.
&FUEL PUMP RELAY
BATTERY
12 V
. . . . . . . . FUSIBLE LINK 15 WAY
439 PNWBLK
419
BRNNVHT
SERIAL DATA
451
WHTIBLK
450 BLWHT
ALDL CONNECTOR
NO "SERVICE ENGINE SOON" "LIGHT
5.OL (VIN E) "F'" SERIES (TBI)
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 (ECM) 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. Battery feed CKT 340 is protected by a
20amp in-
line fuse. If this fuse was blown, refer to wiring
diagram on the facing page of Code 54.
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
@ CKT419open
@ 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.
o Ignition CKT 439 to ECM open.
@ Poor connection to ECM.

DRIVEABILITY AND EMISSIONS 5.OL (VIN E) 6EZ-A-11
@ DISCONNECT ECM CONNECTORS.
@ IGNITION "ON".
@ PROBE CKT 419, WlTH TEST LIGHT
TO GROUND.
- GAGE FUSE. IGNITION "ON". SHORT TO GROUND IN
- FAULTY BULB. 0 PROBE CKT 340 81 439 CIRCUIT THAT HAD A
- OPEN CKT 419. WITH TEST LIGHT TO
- CKT419 SHORTED TO

6E2-A-12 5.OL (VIN E) DRIVEABILITY AND EMISSIONS
TO OIL PRESS. SW. ECM
&FUEL PUMP RELAY
FUSE
& HOLDER BATTERY 12 V . . . . . . . .
FUSIBLE LINK
439
PNWBLK
419 BRNNVHT
- -
451 WHTIBLK
450
BLWHT
ALDL CONNECTOR
8-4-87
55 1235-6E
CHART A-2
NO ALDL DAM OR WON"T FLASH CODE 12
'SERVICE ENGINE SOON" LLlGHT "ON" "STEADY
5.OL (VIN E) "F" "SERIES (TBI)
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
(ECM) will turn the light "ON" by
grounding CKT 419 at the ECM.
With the diagnostic terminal grounded, the light should flash
a Code 12, followed by any trouble code(s)
stored in memory.
A steady light suggests a short to ground in the light control CKT 419, or an open in diagnostic CKT 451.
Test Description: Numbers below refer to circled
numbers on the diagnostic chart.
1. If there is a problem with the ECM that causes
a
"Scan" tool to not read serial data, then the ECM
should not flash a Code
12. If Code 12 does flash,
be sure that the "Scan" tool is working properly on
another vehicle. If the "Scan" is functioning
properly and CKT 461 is OK, the PROM or ECM
may
be at fault for the NO ALDL symptom.
2. If the light goes "OFF" when the ECM connector is
disconnected, then CKT 419 is not shorted to
ground.
3. This step will check for an open diagnostic CKT
45 1.
4. At this point, the "Service Engine Soon" light
wiring is OK. The problem is a faulty ECM or
PROM. If Code 12 does not flash, the ECM should
be replaced using the original PROM. Replace the
PROM only after trying an ECM, as a defective
PROM is an unlikely cause of the problem.

6E2-A-114 5.OL (VIN E) DRIVEABILITY AND EMISSIONS
CHART A-3
(Page I of 2)
ENGINE CRANKS BUT WILL NQ"TRUN
5.OL (VIM E) "F"" SERlES (TBI)
Circuit Description:
This chart assumes that battery condition and engine cranking speed are OK, and there is adequate fuel in
the tank.
Test Description: Numbers below refer to circled
numbers on the diagnostic chart.
1. A "Service Engine Soon" light "ON" is a basic test
to determine if there is a 12 volt supply and
ignition 12 volts to ECM. No
ALIII, may be due to
an ECM problem and CHART A-2 will diagnose
the ECM. If TPS is over 2.5 volts, the engine may
be in the clear flood mode, which will cause
starting problems.
2. No spark may be caused by one of several
components related to the ignition system.
CHART
C-4 will address all problems related to
the causes of a no spark condition.
3. Fuel spray from the injector(s) indicates that fuel
is available. However, the engine could be
severely flooded due to too much fuel.
4. While cranking engine, there should be no
f~lel
spray with injector disconnected. Replace an
injector if it sprays fuel or drips like a leaking
water faucet.
5, The fuel pressure will drop after the fuel pump
stops running due to
a controlled bleed in the fuel
system. Use
of the fuel pressure gage will determine
if fuel
system pressure is enough for the engine to start
and run. The key may have to be cycled
2 or more
times for accurate reading.
6. No fuel spray from injector indicates a faulty fuel
system or no ECM control of injector.
7. This test will determine if the ignition module is
not generating the reference pulse if the wiring or
ECM is at fault. By touching and removing
a test
light to 12 volts on CKT 430,
a reference pulse
should be generated. If
injector test light blinks,
the ECM and wiring are
OK.
Diagnost Aids:
@ Water or foreign material can cause a no start
during freezing weather.
@ An EGR sticking open can cause a low airlfuel
ratio during cranking.
@ Fuel pressure: Low fuel pressure can result in
a very lean airlfuel ratio. See CHART A-7.
@ A grounded CKT 423 (EST) may cause a "No-
Start" or a "Start then Stall" condition.