1988 PONTIAC FIERO fuse chart

1B-8 AIR CONDITIONING
INSUFFICIENT COQblNG "CHART A
A/C FUSE AND/OR GAGE FUSE.
OR DISCONNECTED
AlC WIRE CONNECTOR.
. CHECK BLOWER FOR FAN OPERATION.
. ENGINE COOLING FAN OPERATION (FAN OPERATES IN ALL A/C MODES AS FOLLOWS:
A. DISCONNECT ENGINE COOLANT TEMPERATURE FAN SWITCH.
8. WITH IGNITION ON AND ENGINE NOT RUNNING, SET A/C CONTROL TO A/C MODE.
C. ENGINE COOLING FAN SHOULD RUN.
D. RECONNECT ENGINE COOLANT TEMPERATURE FAN SWITCH.
REPLACE COMPRES-
SOR ASSEMBLY. RE-
PLACE ORIFICE. EVA-
CUATE AND CHARGE. AS
REQUIRED
AND 'HIGH' BLOWER.
T
AUXIL I ARY FAN IN T OF VEHICLE.
I OFF ALL THE TIME I
RESTRICTION IN HIGH
SIDE OF SYSTEM.
VISUALLY CHECK FOR
FROST SPOT TO LOCATE
RESTRICTION. REPAIR.
Figure
8 C.C.O.T. NC System Insufficient Cooling Diagnostic Procedure (1 of 4)

6C-4 ENGINE FUEL
to fully insert the unleaded gas nozzle will result in
gasoline splashing back out of the filler neck.
Fuel Gage Sending Unit
The fuel gage sending unit is attached to the top
of the fuel tank. It is held in place with a cam lock ring
and a gasket is used between the tank and sending unit.
Sending units have three hoses attached. One line
is for the fuel feed. The second line is connected to the
vapor canister, to keep fuel vapor from getting into the
air (see Section 6E). The third line is used as a fuel
return line to the tank.
On some sending units a wire is attached to the
unit. On others the connectors attach directly to the
sender.
When a fuel gage sending unit is removed always
make sure to install the gasket and any power or
ground leads that were removed.
DIAGNOSIS
Fuel system diagnostic procedures are located in
Section(s) 6E1 thru 6E3.
SERVICE PROCEDURES
If the fuel system is suspected of delivering an
improper amount of fuel, it should be inspected and
tested in the vehicle, as follows:
1. Make certain that there is fuel in the tank.
2. With the engine running, inspect for leaks at all
fuel feed pipe and hose connections from
fuel
tank to injection pump. Tighten any loose
connections. Inspect all hoses for flattening or
kinks which would restrict the flow of fuel. Air
leaks or restrictions on suction side of fuel pump
will seriously affect pump output.
FUEL SYSTEM PRESSURE RELIEF
CAUTION: To reduce risk of fire and
personal injury, it is necessary to
relieve duel system pressure before
servicing fuel system components. To
do this:
Remove "fuel pump" fuse from fuse
block in passenger compartment.
e Crank engine - engine will start and run
until fuel supply remaining in fuel lines is
consumed. Engage starter for
3.0
seconds to assure relief of any remaining
pressure.
e With ignition "OFF", replace duel pump
fuse.
Unless this procedure
is followed before
servicing fuel lines
or connections, fuel
spray could occur.
When repair to the fuel system has been
completed, start engine and check all connections that
were loosened for possible leaks.
Refer to Section 6E for additional diagnosis of
engine fuel system.
Fuel Pump Flow Test
1. Test fuel
pump by connecting hose from EFI fuel
feed line to a suitable unbreakable container.
Apply battery voltage to the fuel pump test
terminal (terminal
"G" of ALCL).
2. Fuel pump should supply
1/2 pint or more in 15
seconds.
3. If flow is below minimum, check for fuel
restriction. If there is no restriction, check pump
pressure.
Fuel System Pressure Test
This test must be performed when diagnosing the
fuel system.
CAUTION: To reduce the risk of fire
and personal injury, it is necessary to
relieve fuel system pressure before
servicing fuel system components on
the
TBI system. To do this:
s Remove "Fuel Pump" fuse from fuse block in
passenger compartment.
e Crank engine. Engine will start and run until fuel
remaining in fuel lines is consumed. Crank the
starter for three seconds to assure that any
remaining pressure is relieved.
e With the ignition off, replace the "Fuel Pump"
fuse.
1. Obtain two
sections of
3/8" steel tubing. Each
should be about 254 mm (10 inches) long.
I
Double-flare one end of each section.
2. Install a flare nut on each section. Connect each i
of the above sections of tubing into the "flare nut 1
to flare nut adapters" that are included in J-29658 i
Gage Adapters.
3. Attach the
pipe and adapter assemblies to the
J-29658 gage.
4. Hoist the car.
5. Disconnect
front fuel feed hose from the fuel pipe
on the body.
1
6. Install a
254 mm (10 inch) length of 3/8" fuel
hose onto the fuel feed pipe on the body. Attach 1
I the other end of the hose onto one of the sections
of pipe mentioned in Step 1. Secure the hose
connections with clamps.
7. Attach the front fuel feed hose onto the other
i
section of tubing mentioned in Step 1. Secure the I
hose connection with a clamp. I
8. Start
the engine and check for leaks. I 9. Observe
the fuel pressure reading. It should be 62
to 90
kPa (9 to 13 psi). If not, refer to the I
appropriate Emissions Section.
10. Depressurize
the fuel system and remove the gage I
with adapters. Reconnect the fuel feed hose to the
pipe and torque the clamp to
1.7 N.m (1 5 lb. in.).
11. Lower
the car. Start the engine and check for fuel
leaks.
Fuel System Pressure Test- MPFl
Fuel system diagnosis is in Section 6E3, Chart
A-7.

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.

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-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.

6EZ-C8-4 DRIVEABILITY AND EMISSIONS - 5.OL (VIN E)
I5 WAY (FRONT VIEW)
SPEED INPUT
4rH GEAR SIGNAL
422 TANIBLK
ALDL CONNECTOR
CHART C-8A
TRANSMISSION CONVERTER CLUTCH (TCC)
ELECTRICAL DIAGNOSIS
(Page 1 of 2)
5.OL (VIN E) "F" "SERIES (TBI)
Circuit Description:
The purpose of the automatic transmission torque converter clutch is to eliminate the power loss of the
torque converter, when the vehicle is in a cruise condition. This allows the convenience of the automatic
transmission and the fuel economy of a manual transmission.
Fused battery ignition is supplied to the TCC solenoid through the brake switch. the ECM will engage
TCC
by grounding CKT 422 to energize the solenoid.
TCC will engage when:
- Vehicle speed above 24 mph - Engine at normal operating temperature (above 70°C, 156°F)
- Throttle position sensor output not changing, indicating a steady road speed
- Brake switch closed
Test Description: Numbers below refer to circled solenoids
and relays before installing a
numbers on the diagnostic chart. replacement ECM. Replace
any solenoid or relay
1. Confirms 12 volt supply as well as continuity of that
measures less than 20 ohms.
TCC circuit.
2. Grounding the diagnostic terminal with engine Diagnostic Aids:
"OFF", should energize the capability of the ECM An
engine coolant thermostat that is stuck open or
to control the solenoid. opens
at too low a temperature, may result in an
3. Solenoid coil resistance must measure more than inoperative TCC.
20 ohms. Less resistance will cause early failure
of the ECM
drive^.". Using an ohmmeter, check
the solenoid coil resistance of
all ECM controlled

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.

DRIVEABILITY AND EMISSIONS 2.8L (VIN 5) 6E3-A-l l
CHART A-1
CLEAR CODES AND CONFIRM "CLOSED LOOP " OPERATION AND NO "SERVICE ENGINE SOON" LIGHT.
DISCONNECT
ECM CONNECTORS. BATTERY
FUSE (IN HOLDER)
IGNITION "ON".
PROBE
CUT 419, WITH TEST LIGHT
TO GROUND.
- GAGE FUSE. SHORT TO GROUND IN
- FAULTY BULB. @ PROBE CKT 340 & 439 CIRCUIT THAT HAD A
- OPEN CUT 419. WITH TEST LIGHT TO
- CKT 419 SHORTED TO
REPAIR OPEN IN
GROUNDS OR ECM. CIRCUIT THAT DID NOT
SEE QUAD DRIVER
CHECK (CHART
C-1).