1988 PONTIAC FIERO warning light

WARNINGS AND ALARMS: CHIMES I
(Continued from facing page) (Continued from previous column) B: KEY IN IGNITION INPUT TEST
e Refer to System Diagnosis when a result is
not normal.
SYSTEM DIAGNOSIS
Do the tests listed lor your symptom in the
Symptom Table below.
e Tests follow the Symptom Table.
SYMPTOM TABLE
SYMPTOM DO TEST I
1 None of the Alarms 1 A: Audio Alarm I
(Continued in next column)
A: AUDIO ALARM ASSEMBLY TEST
At: CONVENIENCE CENTER
e Audio Alarm Module Removed
The FASTEN BELTS
chime reminder oper-
ates when the
Seatbelt
is buckled
The FASTEN BELTS
Indicator does not op-
erate, but the
FAS-
TEN BELTS chime
operates
The FASTEN BELTS
Indicator is always on,
but chime operates
properly
Only the Lights-On
Reminder does not
operate
Connect Correct
Between
I Result Diasnosis
C: Fasten Belts
Input Test
D: FASTEN
BELTS Indicator
Test
D: FASTEN
BELTS Indicator
Test
E: Lights-On In-
put Test
If all results are correct and all the
chime functions were not working, re-
place the Audio Alarm Assembly.
1. Check the ORN (140) wire.
2. Check the BLK/WHT (150) wire for an
oDen to ground.
At: CONVENIENCE CENTER
LT GRN (80) and TAN (159) wires for an
open (see schematic).
2. Check Ignition Key Warning Switch and
LT GRN (80) wire for a short to ground
(see schematic).

WARNINGS AND ALARMS: CHIMES
6: FASTEN BELTS INPUT TEST
At: CONVENIENCE CENTER
Ignition Switch: RUN
If the above results are correct, replace
the Audio Alarm Assembly.
Buckle
LH Front
Seatbelt
1. Check PNKIBLK (39) wire for an open.
2. Check the Seatbelt Switch, and BLK (238)
wire for an open (see schematic).
3. Check BLK (238) wire for a short to
ground. If wire is OK, replace the
Seat-
4: FASTEN BELTS INDICATOR TEST
See E (PNKIBLK)
& H (BLK)
Connect: FUSED JUMPER
At: CONVENIENCE CENTER
Condition:
a Audio Alarm Assembly Removed
Connect Correct For
Between Result Diagnosis
Test Lamp
off If
the indicator response was correct, re-
place the Audio Alarm Module.
1. Checklrepair the bulb, the YEL (237)
wire, the BLK (150) wires, and the In-
strument Cluster printed circuit for
opens.
2. Check the Instrument Cluster Printed
Circuit for
a short to Battery.
E: LIGHTS-ON INPUT TEST
At: CONVENIENCE CENTER
0 Audio Alarm Module Removed

WARNINGS AND ALARMS: CHIMES
GlRGUlT OPERATION
The Warnings and Alarms System sounds a
chime to bring attention to one or more of
several conditions. These conditions are:
1) the
lights are on and the Ignition Switch is not in
RUN, BULB TEST, or START;
2) the Igni-
tion key is in the Ignition Switch when the
driver's door is open; and
3) the seatbelt is un-
buckled when the Ignition Switch is in RUN,
BULB TEST, or START.
Voltage is applied at all times through the
STOP
HAZ Fuse to terminal B, to power the
solid state Audio Alarm Assembly.
IGNITION KEY VVARNING
Voltage is applied to the Audio Alarm As-
sembly by the STOP HAZ Fuse. Whenever the
key is in the Ignition Switch and the Ignition
Switch is in LOCK, OFF, or ACCY with the
driver's door open, terminal C of the module is
grounded. This sounds the alarm.
LIGHTS-ON WARNING
When the Light Switch is in HEAD or
PARK, voltage
is applied to the Audio Alarm
Assembly. When the Ignition Switch
is in
RUN, BULB TEST, or START, voltage is
applied through the Gages Fuse to the module.
These two voltages are sensed and the alarm is
not sounded.
When the Ignition Switch is not in RUN,
BULB TEST, or START, the Gages Fuse loses
voltage. The Audio Alarm Assembly senses the
change. If voltage is still available from the
Light Switch, the Lights-On Warning alarm
will sound. The alarm can be turned off by
turning the Light Switch to the OFF setting.
The module no longer senses voltage from the
Light Switch, so the alarm does not sound.
SEATBELT WARNING
With the Ignition Switch in RUN, BULB
TEST, or START, voltage is applied through
the Gages Fuse to the Audio Alarm Assembly.
With the driver's
seatbelt unbuckled, terminal
H of the module is grounded through the Seat-
belt Switch. The FASTEN BELTS Indicator
always goes on for about
5 seconds when the
Ignition Switch is set to RUN, BULB TEST,
or START. The Fasten Belts Chime, however,
only sounds if the
seatbelt is unbuckled and
the Ignition Switch
is in RUN, BULB TEST
or START

INSTRUMENT PANEL: GAGES CLUSTER
TROUBLESHOOTING HINTS COMPONENT LOCATION Page-Figure
* For a list of possible symptoms, go to System Coolant Temperature Sender (VIN E) Lower LH side of engine ....................
Diangosis. Coolant Temperature Sender (VIN F)
....................... .................... * For Instrument Cluster removal and replace- (VIN 8). Lower
LH side of engine
ment procedures, see Section 8C of the Ser- Coolant Temperature Sender (VIN S) Top LN front of engine, behind A/C Compressor.
.................. ..................... vice Manual. Fuel Tank Unit Top center of fuel tank.
..................... ...... * Try the following checks before doing the Sys- Fuse Block. Behind
LH side of IIP, below light switch.
................. tem Check. Ignition Switch. Behind IIP, on
top side of steering co
....... ........... Oil Pressure Sender (VIN E) Top rear of engine, near distributor. 1. Check GAGES Fuse by observing the . ........... Oil Pressure Sender (VIN F) (VIN 8) Top
rear of engine, near distributor.
BRAKE Warning Indicator with the Igni- Oil Pressure Sender (VIN S) ........ Lower LN side of engine .................... tion Switch in RUN and the Park Brake ................ .. el00 (42 cavities) LN
front of dash, left of brake master cylinder
applied.
................. C313 (3 cavities) Below
center of back seat. ...................
2. Check ground 6200. . 6118 (VIN F) (VIN 8) ............. Rear of RN cylinder head. ...................
.................... ................... 3. Check case ground of Coolant Temperature 6118
(VIN S) Rear
of RH cylinder head.
.......................... ............ Sender. 6200 Behind I/P, left of steering column ' h .......................... 4. Check case ground of Oil Pressure Sender. 6304 Under rear seat,
on support bracket
.......................... S204. IIP harness, behind instrument cluster. ........ 5. Check Indicator bulbs. .......................... ........ S205. I/P harness, behind instrument cluster. * Go to System Check for a guide to normal .......................... S217. I/P harness, behind center of IIP .............. operation.
* Go to Systern Diagnosis for diagnostic tests.
SYSTEM CHECK
* Use the System Check Table as a guide to
normal operation. Refer to the diagnosis given
if other results occur.
* Tests follow in System Diagnosis.

INSTRUMENT PANEL: GAGES CLUSTER
I Oil Pressure Gage
(Continued from previous page)
indicates low
pressure
and oil
pressure is good
Coolant
Temperature Gage
does not indicate
HOT with Ignition
Switch in START or
BULB TEST, but
does operate
accurately
Do Test I: (Also see
Test A
terminal B)
Check DK GRN (35)
wire and Ignition
Switch for opens
Repairlreplace as
necessary
Oil Pressure Gage
indicates high
pressure at
all times
and oil pressure is
good Do
Test
J: (Also see
Test A terminal
8)
Oil Pressure Gage is
inaccurate Do
Test K: (also see
Test A terminal
8)
Do Test L
Tachometer does not
operate
Speedometer1
Odometer is
inaccurate Do
Test M
Do Test N: (with
5-33431-873 harness
connector available)
One or both
Odometers do not
operate properly,
but Speedometer
operates accurately
I
Check the
Instrument Cluster
Printed Circuit for
cracks or flaws
Replace the
Speedometer1
Odometer Assembly
(Continued in next column) (Continued from previous
column)
Hi Beam Indicator
does not operate
properly See
Exterior lights
Section 8A-110
(Also see Test
B
terminal 8)
I operate properly
I
(Also see Test A
I
Seatbelt Indicator
and alarm do not
BRAKE Warning Indicator does not
work properly
I
See Warnings and
Alarms (see Index)
SERVICE
ENGINE SOON
Indicator does not
does not work See
Brake Warning
System, Section
8A-41 (Also, see
Test A terminal
1)
See Section 6E of
1 Service Manual
Do Test O
r
(Also, see Test B
terminals 7 and
9)

INSTRUMENT PANEL: DIGITAL CLUSTER n 23 rn E
ClRCUlT OPERATION
The Instrument Cluster uses a microprocessor
to develop data for fuel supply, coolant tem-
perature, oil pressure, voltage, engine rpm, and
vehicle speed. The Digital Cluster also contains
an Odometer, Warning Indicators, and an Audi-
ble Alarm. The Audible Alarm signals low oil
pressure, high temperature, low or high voltage,
and low fuel.
With the Ignition Switch in RUN, voltage is
applied through the GAGES Fuse to the Battery
Power inputs of the Instrument Cluster. With the
Light Switch in PARK or HEAD, voltage is ap-
plied at all times to the Lights On Dim Input.
The car's speed is displayed in mph or
krnh by
selecting either English or Metric with the
En-
glishNetric selector switch.
Gages and Audible Alarm
With the Ignition Switch in RUN, voltage is
applied through the GAGES Fuse to the Battery
Power Input terminal. With the Light Switch in
PARK or HEAD, voltage is applied at all times
to the Lights On Dim Input.
Fuel Display
The Fuel Display Sender provides a signal to
the cluster that is related to fuel level. With a
full tank the resistance is 90 ohms, and with an
empty tank the resistance is less than
1 ohm.
The microprocessor converts this signal and
activates a 12 segment bar graph which dis-
plays the fuel level. When the bar graph fuel
gage display changes from two segments to
one, the Audible Alarm beeps briefly.
Oil Pressure Display
The Oil Pressure Sender, with a resistance of
0 to 90 ohms, sends a signal to the cluster that is
related
to oil pressure. At zero pressure (0 PSI),
resistance is 0 ohms, and at maximum pressure
(80 PSI), resistance is approximately 90 ohms.
The microprocessor converts the signal and
activates a 12 segment bar graph which dis-
plays the oil pressure. When the bar graph
changes from two segments to one segment
(approximately
4 PSI), the Audible Alarm
beeps briefly.
kmperature Display
The Coolant Temperature Sender sends a sig-
nal to the Instrument Cluster that is related to
coolant temperature. Coolant Temperature
Sender resistance drops from 1,365 ohms at
100°F
(38"C), to 55 ohms at 260°F (127°C). The
temperature display is a bar graph display with
12 segments. When the bar graph changes to all
segments activated (hot coolant temperature),
the Audible Alarm beeps.
Volts Display
The microprocessor in the gages module re-
ceives a signal from the Battery Power Input ter-
minal. This signal activates the 12 segment bar
graph volts display. The volts gage ranges from 8
volts
(1 segment lit) to 18 volts (all segments lit).
Under idling and normal driving conditions, 7 or
8 segments are lit. When the volts gage displays
less than
4 segments or more than 12 segments,
the Audible Alarm beeps.
Tachometer
The Thchometer displays engine speed in rpm.
Voltage pulses are taken from the
Ignition Sys-
tem and sent to the Tachometer. Solid state cir-
cuits process these pulses into a signal that con-
trols the Tachometer display. The Tachometer
responds to the frequency of the voltage pulses,
the number of pulses in a second. This increases
with engine speed. The
'Pdchometer Filter in the
circuit rounds off the pulses and removes voltage
spikes.
Speedometer
The digital Speedometer is operated by an
electronic circuit. The Vehicle Speed Sensor, lo-
cated in the Transmission, generates an AC volt-
age whose frequency is proportional to the speed
of the vehicle. This goes to the Vehicle Speed
Sensor Buffer and then to the Speedometer cir-
cuit board in the Instrument Cluster. The solid
state circuit processes this signal into a control
signal for the Speedometer display.
Odometer
The digital Odometer display is operated by an
electronic circuit. The Vehicle Speed Sensor, lo-
cated in the Transmission, generates an
AC volt-
age whose frequency is proportional to miles
(kilometers) traveled. This goes to the Buffer
and then to the Odometer circuit board in the
Instrument Cluster. The solid state circuit
processes this signal into a control signal for
the Odometer display. Distance Data is stored
in
NV RAM Chip.

DRIVER INFORMATION CENTER (DIC)
SYSTEM CHECK TABLE
ACTION NORMAL OPERATION
Press the SYS CHK button on the DIC display
With
all the doors closed, open the LH door
Leave the LH door open, and open the RH door
Leave both doors open, and open the
t
Driver Information Center (DIC) Display comes
on
Parts of the vehicle symbols (LCD) light up
in
sequence
The following messages are scrolled, or spelled
out as they move across the Display:
RIGHT DOOR AJAR
FRONT LAMP
LEFT DOOR AJAR
REAR LAMP
LOW COOLANT
LOW WASHER FLUID
HATCH AJAR
PONTIAC SYSTEMS OK
Audible Warning will sound twice when the
PONTIAC SYSTEMS OK displays at the end of
the routine
The start-up routine is repeated as described
when the Ignition Switch is turned to RUN
in - Step 1
LH door of vehicle symbol lights
LEFT DOOR AJAR
is displayed
LH and RH doors of vehicle symbol are
lit
RIGHT DOOR AJAR is displayed
LH and RH doors and trunk of vehicle symbol
are lit
TRUNK AJAR is displayed for
2 seconds '
RIGHT DOOR AJAR is then displayed
0 Refer to System Diagnosis when a result is not normal.
SYSTEM DlAGNOSlS
Do the tests listed for your symptom in the
Symptom Table below or when directed by
the System Check.
Tests follow the Symptom Table.
SYMPTOM TABLE
ights and message
s displayed when
he reservoir is not
ed with the
er fluid
reser-
(SYMPTOM TABLE continued on next page)

DRIVER INFORMATION CENTER (DIC) I $
(Continued from previous page)
I: DOOR AJAR OPEN SWITCH TEST
At: SUSPECT DOOR AJAR SWITCH
CONNECTOR (Disconnected)
(see schematic).
2. Check the wire at terminal B for an open
(see schematic).
CIRCUIT OPERATION
The Driver Information Center (DIC) dis-
plays warnings about
saftey conditions in the
vehicle. The location of the condition is indi-
cated in a car symbol, where segments of the
symbol are
lit. Seven displays that form letters
light up to spell out the condition, such as LOW
COOLANT. The car symbol and the letters are
made by Liquid
Crystal Displays (LCD) that
are turned on by a solid state microprocessor.
Door and trunk switches that are closed with
the door open (like interior light switches) are
connected to the DIC Display. These ground
the DIC inputs if the door or trunk is not closed
tightly, and then the display illuminates the
warning. The Washer Fluid Level Switch works
in the same way.
It closes when the windshield
washer fluid is low.
The Low Coolant Probe is not a switch that
opens and closes.
It has a very high resistance
to ground, more than 50,000 ohms, when the
engine coolant level is low. This causes the DIC
Display to light the LOW COOLANT w
With more of the probe covered by coolant, its
resistance decreases. When the fluid level is
good, the resistance
will be less than 10,000
ohms. With the probe resistance between
10,000 and 50,000 ohms, the probe is partly
covered and the fluid is not low enough to cause
the warning to be displayed. Burned
out light bulbs in the vehicle are
detected by the Lights Monitor. The power feed
from a switch to a bulb circuit contains
resistance wire. This is connected between the
switch and the Lights Monitor Module.
If the
bulb is on properly, the current through the
resistance wire causes a small voltage drop, less
than one volt. When a bulb burns out, there is
no current through it
and the voltage drop at
the module is missing. The Lights Monitor
Module detects this battery voltage at one of its
inputs (instead of slightly lower voltage) and
closes a solid state switch in the Module to
g to appear in the DIC Display.