1988 PONTIAC FIERO light

COOLANT FAN I $
A: COOLANT FAN OPEN TEST (TABLE
3)
Connect: FUSED JUMPER
At: COOLANT FAN RELAY CONNECTOR
(Disconnected)
Jumper Correct Result For Diagnosis
Between
1. Leave fused jumper in place and go to
Table
4.
E (RED) & A
(BLKIRED)
A: COOLANT FAN OPEN TEST (TABLE
41
Connect: TEST LAMP
At: COOLANT FAN CONNECTOR
(Disconnected)
Condition:
Fused jumper in place from Table
3.
If the Coolant Fan runs, replace the
Coolant Fan Relay. Coolant
Fan
runs
-. -. See --
B: COOLANT FAN SWITCH TEST
Connect
Between
B (BLKtRED)
& Ground
B (BLKIRED)
& A (BLK)
Connect: FUSED JUlVlPER
At: COOLANT FAN SWITCH CONNECTOR
(Disconnected)
Condition: lgnition Switch: RUN
Jumper
Between Correct
Result For Diagnosis
Coolant Fan
Ground
runs
If the Coolant Fan runs replace the
Coolant Fan switch.
1. Check BLK (335) wire for an open (see
schematic).
6: AIC CONTROL HEAD TEST
If the results are correct, replace the
Coolant Fan.
1. Check BLKIRED (532) wire for an open.
2. Check BLK (150) wire for an open.
Correct Result
Test Lamp
lights
Test Lamp
lights
Connect: FUSED JUMPER
At:
A/C CONTROL HEAD CONNECTOR Cl
(Disconnected)
Condition:
lgnition Switch: RUN
For Diagnosis
See 1
See 2
Jumper
Between I Correct Result I For Diagnosis I
".' Ground
J (DK GRN) & Coolant Fan See N (BLK) runs
If the results are correct, replace the
AIC
Control Head.
1. Check DK GRNIWHT (335) and DK GRN
(535) wires for an open (see schematic).
2. Check BLK (150) wire for an open (see
schematic).
D: COOLANT FAN SHORT TEST
1. With the Ignition Switch in RUN, remove
the Coolant Fan Switch.
If the fan continues to
run, go to step 2.
If the fan turns off, replace the Coolant Fan
Switch.
2. Remove the CIH-FAN Fuse.
If the fan turns off, go to step 3.
If the fan continues to run, replace the
Coolant Fan Relay.
3. Disconnect the
AIC Control Head and recon-
nect CIH-FAN Fuse.
If the fan continues to run,
check the DK
GRNIWHT (335) and BLK (335) wires for a
short to ground.
If the fan turns off, replace the
AIC Control
Head.
CIRCUIT OPERATION
V6 VIN S, V8 VIN F and V8 VIN 8
The Coolant Fan is controlled by the Elec-
tronic Control Module (ECM). In the V6 VIN S,
the Coolant Fan is also controlled by the Redun-
dant Cooling Fan Switch. When the ECM
grounds the 335 circuit, the Coolant Fan Relay
is energized and battery voltage is applied to
the Coolant Fan.
If the ECM fails (V6 VIN S),
the Redundant Cooling Fan Switch will ground
the 335 circuit and energize the Coolant Fan
Relay. The ECM will ground the Coolant Fan
Relay when the Coolant Temperature Sensor
indicates the coolant temperature is greater
than 106
OC (222 OF) or when the AIC Control
Head pressure is greater than 233 psi (1600
kPa) and the vehicle speed is less than 40 mph.

VEHICLE SPEED SENSOR
TROUBLESHOOTING HINTS
0 Try the following checks before doing the
System Diagnosis
.
1
. Check the Gages Fuse by observing the Brake
Indicator when applying the Parking Brake
wrth the Ignition Switch in RUN (engine not
running)
.
2 . Check ground 6118 .
3 . If only the Speedometer or only the Odometer
does not work. replace the suspect item
.
Go to System Diagnosis for diagnostic tests .
SYSTEM DlAGNOSlS
Do the tests listed for your symptom in the
Symptom Table below
.
Tests follow the Syrnptom Table .
COMPONENT LOCATION Page-Figure
Cruise Control Module
............ Behind RN side of IlP ...................... 201-11-A
Electronic Control Module (ECM)
... Behind RN side of IIP ...................... 201-12-B
Fuse Block
...................... Behind LN side of IIP. below light switch ....... 201-10-A
Vehicle Speed Sensor
............. Lower LEI rear of transmission ............... 201- 8-D
Vehicle Speed Sensor Buffer
....... Behind RH side of IIP. near ECM ............. 201-13-A
ClOO (42 cavities) ................ LN front of dash. left of brake master cylinder .. 201- 0-A
C207 (15 cavities) ................ Behind RH side of IIP. near ECM ............. 201-13-A
C209 (2 cavities)
................. Behind RN side of IIP. left of Cruise Control
................................. Module 201-11-A
6118 (VIN E)
................... Rear of RH cylinder head .................... 201- 5-B
6118 (VIN F) (VIN 8) ............. Rear of RN cylinder head .................... 201- 5-A
6118 (VIN S)
.................... Rear of RN cylinder head .................... 201- 1-C
S143 (VINE)
.................... Engine harness. RH front of dash ............. 201- 2-A
S143 (VIN F) (VIN
8) ............. Engine harness. RN front of dash ............. 201- 6-A
S143 (VIN S)
.................... Engine harness. center front of dash ........... 201- 1-A
S202
........................... IIP harness. behind RH side of IIP ............ 201-13-A
S204
........................... IIP harness. behind instrument cluster ......... 201-10-A
S217 ........................... IIP harness. behind center of IIP .............. 201-10-A
SYMPTOM TABLE
I SYMPTOM I FOR DIAGNOSIS I
=liter does not operate properly. ECM I Do Test B
code 24 is not set
ECM Code
24 is set. Speedometer is good
e If your symptom is not listed in the Symptom Table. pedorm all the tests .
Do Test C
See Section 6E of Service Manual
Speedometer does not operate properly. and ECM
Code
24 is set
Cruise Control does not operate properly. ECM
Code
24 is not set Do
Test
A
Do Test D

CRUISE CONTROL
TROUBLESHOOTING HINTS
Try the following checks before doing the Sys-
tem Check
.
1 . Check vacuum hose for leaks. kinks. andlor
restrictions . Also check Cruise Control
Servo linkage
. Refer to Section 9 for vacuum
hose routing and servo linkage adjustments
.
2 . If the system works except for the Tap-Up
and
TapDown functions. replace the Cruise
Control Module
.
Go to System Check for a guide to normal
operation
.
Go to System Diagnosis for diagnostic tests .
SYSTEM CHECK (ROAD TEST)
Use the System Check Table as a guide to
normal operation
.
COMPONENT LOCATION Page-Figure
Brake Switch
.................... Above brake pedal. on brake pedal support ..... 201- 9-A
Check Valve
..................... Behind engine. to right of master brake cylinder . 201-15-A
Clutch Switch
................... Above clutch pedal. on clutch pedal support .... 201-10-B
Cruise Control Module
............ Behind RH side of IIP ...................... 201-11-A
Cruise Control Servo .............. LH front of engine compartment ............. 201-15-A
Fuse Block
...................... Behind LH side of IIP. below light switch ....... 201-10-A
Vacuum Release Valve
............ Above brake pedal. on brake pedal support ..... 201-10-B
Vacuum Tank ................... Lower LH front corner of engine compartment .. 201-15-A
Vehicle Speed Sensor Buffer
....... Behind RH side of IIP. near ECM ............. 201-13-A
C203 (6 cavities) ................. Behind LH side of IIP. at base of steering column 201-11-A
C207 (15 cavities) ................ Behind RH side of IIP. near ECM ............. 201-13-A
C209 (2 cavities) ................. Behind RH side of IIP. left of Cruise Control
................................. Module 201-11-A
C223 (4 cavities) ................. Behind LH side of IIP. at base of steering column 201-11-A
6102 .......................... LN rear corner of engine compartment ......... 201-15-A
6118 (VIN E)
................... Rear of RH cylinder head .................... 201- 5-B
6118 (VIN F) (VIN 8)
............. Rear of RN cylinder head .................... 201- 5-A
6118 (VIN S)
.................... Rear of RN cylinder head .................... 201- 1-C
S143 (VIN E) .................... Engine harness. RH front of dash ............. 201- 2-A
S143 (VIN
F) (VIN 8) ............. Engine harness. RN front of dash ............. 201- 6-A
S143 (VIN S)
.................... Engine harness. center front of dash ........... 201- 1-A
S204
........................... IIP harness. behind instrument cluster ......... 201-10-A
S217
........................... IIP harness. behind center of IIP .............. 201-10-A
S238
........................... Cruise control harness. near Brake Switch ...... 201-11-A
SYSTEM CHECK TABLE
Car should maintain speed
(Continued on facing page)

CRUISE CONTROL 2
I Slide Cruise Control Switch momentaril~ to RIA I Car should accelerate to former set s~eed I
(Continued from facing page)
--
While cruising, accelerate, then remove foot I car should coast back to set speed
from accelerator
Release Cruise Switch
back to ON
Tap brake pedal
I While cruising, tap Cruise Switch to RIA I Car should increase 1 mph for each tap, up to I
Car should hold new faster speed
Car should coast slower (Cruise disengages)
tap
until 25 mph is reached when cruise
Control will not o~erate I
While cruising, tap Set button
1 Slide Cruise Switch to OFF ten
taps, then system must be reset to a new
speed
Car speed should decrease by
1 mph for each
I Cruise Control turns off 1
0 Refer to System Diagnosis when a result is not normal.
SYSTEM DIAGNOSIS
@ Use the isolation Test below to choose the
proper diagnostic tests.
@ Tests follow the Isolation Test.
Note: Do not press both the SET and RIA
Switches at the same time while the
engine is running. If the Quick Checker
displays
a short light, release the
switches immediately. Shorts can
damage the Quick Checker.
lSOLATlON TEST
Connect: QUICK CHECKER (J-34185, SPECMO QC-3 OR EQUIVALENT) or VOLT-OHMMETER
At: CRUISE CONTROL MODULE CONNECTOR (Disconnected)
Conditions:
@ Ignition Switch: RUN
Test with Quick Checker
(J-34185 or equivalent) or Digital Meter
Test Condition
Cruise Switch OFF
(ISOLATION TEST continued on next page)
All Lights Off
With Quick
Checker,
Correct Response
-
20 VDC
20 VDC
For
Different
Response, Do
Test:
B
Without Quick Checker,
Using a Digital Meter
A&J
M&J
Meter
Range
200 ohms
0 volts
0 volts
Connector
Terminals
J & Ground
A
Correct
Response
0 ohms

CRUISE CONTROL
(ISOLATION
Test
2 3
4
5
6
7
If all
TEST continued from previous page)
Condition
Cruise Switch ON
Cruise Switch ON, Set Switch
pressed
Cruise Switch
in RIA
Cruise Switch ON, drive wheels
turned by hand
Run engine for one minute, then
turn it off. With Ignition Switch in
RUN, and holding Cruise Switch
in
RIA, press Set Switch, wait for
Servo to pull
in and release Set
Switch
Quick Checker not connected
the responses were correct, replace Cruise
With Quick
Checker,
Correct Response
ONIOFF Light On
BRK Light On
VENT Light On
VAC Light On
SPS Light On
RA Light Off
SC Light Off
SC Light On
VAC
& SNORT Lights Off
ONIOFF Light On
RA Light On
VENT & SNORT Lights
Off
VSS Light flashes On and
Off
Vacuum holds the servo
all theway in
-
Control Module and check
Without Quick Checker, For
Using
a Digital Meter Different
Meter
Range
20 VDG
20 VDC
200 ohms
200 ohms
200 ohms
20 VDC
20 VDC
20 VDC
200 ohms
20 VDC
20 VDC
200 ohms
20VDC
Connector Terminals
A&J
G&J
C&J
K&J
F&N
M&J
L&J
L&J
K&J
A&J
M&J
C&J
A&D
Response,
Correct Do
Response Test
Battery voltage B
Battery voltage C
30 to 55 ohms D
30 to 55 ohms E
15 to 25 ohms F
0 volts A
0 volts
A
Battery voltage G
30 to 55 ohms N
Battery voltage A
Battery voltage
I
30 to 55 ohms J
Pulses between
approximately battery
voltage and less than
7 K, L
volts
Connect fused jumper from
CtoMandfromKtoL
before operating switches
200ohms 1 F&J
for proper operation.
Vacuum holds the servo
all the way in M
Over range N

CRUISE CONTROL
(Continued from previous page)
TEST I: RIA CIRCUIT OPEN
Disconnect C223 and check switch continuity
between terminals A (BLU) and C (YEL) of the
pin half of the Cruise Switch in RIA.
0 If the switch is open, replace the Multi-Func-
tion Lever.
If the switch is not open, check for an open in
the
GRYIBLK (87) wire between terminal C
of connector C223 at terminal M of the Mod-
ule.
TEST J: VENT CIRCUIT SHORT
Remove the connector from the Servo and mea-
sure resistance between terminals
A and C of
the Servo.
If it is less than 30 ohms, replace the Servo.
If it is 30 ohms or more, check for a short to
ground in the DK
BLUIWHT wire from ter-
minal C of the Module to terminal A of the
Servo.
TEST K: VSS ClRCUlT OPEN
If the VSS light does not come on, or the volt-
age between terminals A (GRY) and D (BRN)
remains less than 7 volts, check for an open in
the BRN (437) wire or the RED (381) wire from
the Vehicle Speed Sensor Buffer. Refer to page
33-0 for diagnosis of Vehicle Speed Sensor.
TEST L: VSS CIRCUIT SHORT
If the VSS lights does not go off or Battery
voltage remains between ter
and D
(BRN), check for a short to ground on the
BRN (437) wire or the RED (381) wire from the
Vehicle Speed Sensor Buffer. Refer to page 33-0
for diagnosis of Vehicle Speed Sensor.
TEST M: VACUUM SYSTEM
1. Check for a blocked or leaking vacuum
source.
2. If the vacuum source is good, plug the Vac-
uum Release Port and repeat Test
6 of the
Isolation Test.
If the vacuum now holds the throttle open,
replace or repair the Vacuum Release Valve
or the hose to it.
If the test still fails, replace the Cruise Con-
trol Servo.
TEST N: SPS CIRCUIT SHORT
Disconnect the Cruise Control Servo connector
and repeat Test 7 of the Isolation Test.
If the resistance is now over range, replace
the Cruise Control Servo.
If the resistance is still low, find and repair
the short in the TAN wire from terminal F of
the Cruise Control Module to terminal B of
the Cruise Control Servo.
ClRCUlT OPERATION
The Cruise Control System operates a
mechanical linkage to the throttle by means of a
Vacuum Motor. This is a diaphragm moved by
a vacuum applied to one side. A solenoid oper-
ated valve connects the Vacuum Motor to a
Vacuum Tank. Another solenoid valve vents
the vacuum to reduce the suction. The Cruise
Control Module controls the Vacuum Motor
and the throttle by pulsing these solenoid
valves on and off.
One input to the Module is the vehicle speed.
This input comes from the Vehicle Speed Sen-
sor. If the actual speed signal is different from
the speed that was set into and remembered by
the Module, the Module generates pulses to
change the vacuum and return the vehicle to
the set speed. The Vehicle Speed Sensor is
mounted on the Transmission. Other inputs to
the Module are from the Cruise Switch and the
Set Switch. A disengage input to the Module
comes from a switch on the brake pedal. A
sepe-
rate vacuum shut down of the Cruise Control
comes from the Vacuum Release Valve on the
brake pedal.
The two outputs of the Cruise Control Mod-
ule operate the coils of the Vacuum Valve and
the Vent Valve. Both valves are located in the
Cruise Control Servo. These valves move the
throttle be means of the Vacuum Motor. The
Servo Position Sensor
(SPS) coil senses the
position and motion of the Vacuum Motor. It
feeds this information back to the Module to
provide smooth acceleration while the vehicle is
in Cruise Control.

HORNS
TROUBEESHOOTlNG HINTS
Try the following checks before doing the
System Diagnosis.
1. If the Horns do not sound at all, check the
CTSY Fuse by operating the Cigar Lighter.
2. If only one Worn sounds, check the DK GRN
(29) wire and the suspect Horn.
Go to System Diagnosis for diagnostic tests.
SYSTEM DIAGNOSIS
Diagnostic steps for the symptoms listed in
the following table are listed after the table.
SYMPTOM TABLE
A: The Horns sound continuously
B: None of the Horns sound
A: THE HORNS SOUND
GONTlNUOUSLY
COMPONENT LOCATION Page-Figure
.............. Convenience Center Behind IIP, to
right of steering column. ........ 201-10-A
..................... ...... Fuse Block. Behind LH side
of I/P, belour light switch. 201-10-A
.................... Horn Switch Below
steering wheel hub
....................... Slip Ring Below
steering wheel hub
................ el00 (42 cavities) LH front of dash, left of brake master cylinder .. 201- 0-A
................ C210 (11 cavities) Behind IIP, on
RW lower side of steering column. 201- 9-A
.......................... S203. IIP harness, behind instrument cluster. ........ 201-10-8
B: NONE OF THE MORNS SOUND
(TABLE a,
Connect: TEST LAMB
IiENcE CENTER
I Condition:
a Horn Relay disconnected
Connect
Between I ","d::r I For Diagnosis
A (ORN) &
Ground
B: NOME OF THE HORNS SOUND
(TABLE 21
Horn Switch: ON
Jumper
Between
Test
Lamp lights
(Continued on next page)
See 1
See 2 A (ORN) &
B (BLK)
If all the results
are correct, go to Table 2.
1. Cheek the ORN (40) wire for an open (see
schematic).
2. Check the BLK (28) wire and the Horn
Switch for an open (see schematic).
Test
Lmp lights

BRAKE VVARNlNG SYSTEM
TROUBLESHOOTING HINTS
0 Try the following checks before doing the
System Diagnosis.
Check the GAGES Fuse and PNKIBLK
(39) wire by observing the VOLTS or
SERVICE ENGINE SOON Indicator with
the Ignition Switch in RUN and the engine
OFF.
0 Go to System Check for a guide to normal
operation.
0 Go to System Diagnosis for diagnostic tests.
SYSTEM CHECK
Use the System Check Table as a guide to
normal operation.
e Refer to System Diagnosis for a list of symp-
toms and diagnostic steps.
SYSTEM CHECK TABLE
RUN position to
BULB TEST
COMPONENT LOCATION Page-Figure
.................. Brake Fluid Level Switch. ......... Below brake fluid reservoir 201-16-A
..................... Fuse Block. Behind
LH side of IIP, below light switch. ...... 201-10-A
................. Ignition Switch. Behind IIP, on
top side of steering column ...... 201- 9-A
Parking Brake Switch.
............ In console, at base of parking brake ........... 201-12-D
................... Release Relay Taped
to IIP harness, behind RH side of IIP. .... 201-13-A
................ (2100 (42 cavities) LR
front of dash, left of brake master cylinder .. 201- 0-A
........................... S204. IIP harness, behind instrument cluster. ........ 201-10-A
.......................... ............... S228. IIP harness, above Fuse Block. 201-10-A
SYSTEM DIAGNOSIS
0 Diagnostic steps for the symptorns listed'in
the following table are listed after the table.
A: BRAKE INDICATOR REMAINS ON
WITH THE
IGNITION SWITCH IN
RUN AND THE PARK BRAKE OFF
(TABLE
1)
SYMPTOM TABLE
A BRAKE Indicator remains on with the
Ignition Switch
in RUN and the park
brake off
B BRAKE Indicator lights with the park
brake applied, but does not light when
brake fluid level is low
C BRAKE Indicator does not light at all
D BRAKE Indicator lights with the Igni-
tion Switch in BULB TEST, but does not
light when the park brake is applied
E BRAKE Indicator lights with the park
brake applied, but does not light when
the Ignition Switch is in BULB TEST
Refer to System Diagnosis when a result is
not normal. Disconnect:
CONNECTOR
At: BRAKE FLUID LEVEL SWITCH
Conditions:
0 Ignition Switch: RUN
0 Park Brake: OFF
Pressure Warning
If the result is correct, refer to Section
5 to
test the Brake Hydraulic System.
Replace the Brake Fluid Level Switch if
the Brake Hydraulic System is OK.
1. Go to Table2.