sensor PONTIAC FIERO 1988 Service Repair Manual

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.

AUTOMATIC DAY-NIGHT MIRROR
(Continued from previous page)
SYSTEM DIAGNOSIS
0 Do the tests below if the Automatic Day-Night
Mirror does not operate correctly.
AUTOMATIC DAY-NIGHT MIRROR
VOLTAGE TEST
CONNECTOR (Disconnected)
1. Check BLK and LT GRN (24) wires for an
open. If Back Up lights do not operate,
check Gear Selector Switch adjustment
(automatic) or Back Up Switch
adjust-
:Continued from previous column)
2. Check Gear Selector Switch adjustment
(automatic) or Back Up Switch adjust-
ment (manual). Replace suspect switch if
adjustment does not correct the problem.
3. Check BLK and RED (39) wire for an
open.
4. Check BLK (150) wire for an open.
CIRCUIT OPERATION
The Automatic Day-Night Mirror is auto-
matically moved to the DAY and NIGHT posi-
tions as light conditions change. The Headlight
and Ambient Sensors read the light conditions
and feed this information to the solid state
mir-
ror control unit. The control unit activates the
Motor that drives the mirror.
With the Gear Selector
in Reverse, battery
voltage is applied through the Gear Selector
Switch or Back Up Switch to the reset input of
the mirror. If the mirror is in the NIGHT posi-
tion,
it changes to the DAY position. This pro-
vides a clear view for backing the car.
A distance or sensitivity control changes the
brightness required from the headlights of the
car behind to cause the
mirror to shift to the
NIGHT position.

RADIO I
(Continued from previous page) from back of Radio
If noise persists with replacement antenna, the
problem must be repaired at the source of noise
(generator, ignition system, accessory, etc.). See
Delco Manual for noise "Sniffing" procedures.
Ignition Noise
Trv the following. fixes in the piven order: 8. Install a braided ground strap on the hood. Replace
defective antenna with a good antenna.
If noise disappears repair or replace the defective
antenna. Check antenna ground, Coaxial Cable
Braid, and ground at connectors.
unplugged
- -
1. Check
for loose or defective spark plug wire.
2. Check for defective spark plug.
3. Move all wiring away from Ignition System
and spark plug wires. Antenna
noise
4. Reroute spark plug wires laying against
anything that could possibly transmit noise
to the Radio (car
g or sensor leads that
travel into the passenger compartment).
5. Inspect Ignition system for the following
and replace if necessary:
r Distributor cap carbon ball eroded away,
cracked or loose cap.
A rotor with burned black spot on wiper or
pits in wiper surface.
r A defective coil.
r An oily film on some of the lead terminals or
inside the cap.
Defective
WE1 module; can cause ignition
noise on
FM only.
6. Replace distributor cap and rotor.
9. Check Heater Core ground; clean or install a
braided ground strap if necessary.
10. Check air conditioner accumulator ground;
clean or install a braided ground strap if
necessarv.
TO STEERING
BRAIDED
GROUN GO LUMN
Figure 1 - Gut the BLACK (ground) wire from
the black plug
at the back of the Radio and run
7. Check the ground from engine to firewall, a braided ground strap from the ease of the
install a braided ground strap if necessary. Radio to good, unpainted body ground.
(TRY GROUNDED AND UNGROUNDED)
POWER LlNE TO RADIO
(IGNITION OR MEMORY)
Figure 2 - install a 1224205 filter package.

-. COMPONENT LOCATION VIEWS
PRESSURE WBPER MOTOR FUEL
COO LAMT CUT-OBIT MODULE
TEMPERATURE SMITGH C2
SENSOR CBSMMECTBBR
CONNECTOR
FUEL SWITCH (WITHOUT GAGES)
PUMP
SWITCH
STEERING
SWITCH
12H8.1
Figure A - LN Side Of VIN S Engine Cornpartwent
TEMPERATURE
Figglare B - Top LH Frcswt Of VIM S Engine
COLD
START
INJECTOR
Figure G - Top LN Rear Of VIN S Engine

COMPONENT LOCATION VIEWS
I
MASS AI R FUELPUMP EANlSTER (MAT) SENSOR
FLOW IN-LINE IN-LBNE PURGE FAN PRESSURE
FUSE FUSE
SOLENOlD SVVlTEH
VALVE
12H7.1
- - Figure A - VIN S Engine CompaFtment
Figure B - Lower LN Front Of VIM S Engine
. SPARK TlMlNG
--
Figure C - Top LM Rear Of VlN S Engjne

COMPONENT LOCATION VIEWS IS
FRo&, MANIFOLD ABSOLUTE IDLE AIR
) PRESSURE (MAP) CONTROL ELECTRONIC SPARK
SENSOR STEPPER CONTROL
(ESC)
MOTOR MODULE
CONNECTOR
I
VVASNER
S143
S172 MOTOR
S120 CONNECTOR
S174 S127
AIR SELECT
JUNCTION
A, B AND J AND DIVERTER BLOCK
VALVES FUSIBLE
LINKS
N AND K LOW
COOLANT
Figure B
- RN Front Of Radiator (Except VIN S)
Figure C - LN Side Of Radiator (VlN S)

COMPONENT LOCATION VIEWS I?
MANIFOLD AIR
TEMPERATURE
h
(MAT) SENSOR
EXHAUST GAS
RECIRCULATION
(EGR) SOLENOID
IGNITION
COIL
THROTTLE POSITION
-- -
SENSOR
FUEL
INJECTORS
SWITCH COMPRESSOR
TCN
CONNECTOR
FUSIBLE (DIODE INSIDE)
LINK ti 12Hll.l
Figure A - RN Side Of VIN E Engine Compartment
STARTER
FeOlyr DETONATION
SOLENOID SENSOR
a
Figure B - RH Front Of VlN E Engine Figure
C - Lower RH Side Of VIN E Engine Figure
D - Top LN Front
Of VIN E Engine
Figure E -Top Rear Of
VIN F Engine
(VIN 8 Similar)

COMPONENT LOCATION VIEWS I $
6143 COOLANT
TEMPERATURE
SENDER (WITH
GAGES) OR
SWITCH (WITHOUT
GAGES)
FUEL
1) F~oer PUMP
OF c.4 Fj SWITCH
12H21.3
Figure A - Lower LH Side Of VIN F Engine
(VIN 8 Similar)
Figure
B - Lower LH Front Of VIN F Engine
(VIN 8 Similar) THROTTLE
POSITION
START
WITCH 12H20.2
Figure C - Front Of VIN F Engine (VIM 8 Similar)
SENSOR
12H22.1
Figure D - LH Side Of Transmission (Manual
Shown, Automatic Similar) Figure
E
- Center Frcpt Of Dash
Figure
F - LN Side Of Manual Transmission

HARNESS CONNECTOR FACES
BLK
MASS AIR FLOW SENSOR
(V8 WIN F) (V8 WIN 8)
V00526.2
WHT
OUTSIDE MIRROR SWITCH
V00184 2
PASSENGER'S LUMBAR CONTROL SWITCH,
SEE DRIVER'S LUMBAR CONTROL SWITCH
, PASSENGER'S LUMBAR VALVE ASSEMBLY,
1 SEE DRIVER'S LUMBAR VALVE ASSEMBLY
C2 BLK C1 CRY
RADIO (WITH SUBWOOFER)
~00320 0
C4 BLK
C1 BLK
C2 WHT
C3 BLU
RADIO (WITHOUT SUBWOOFER AND
UK3)
V00236 1
C2 BLK
(C218 WITH UK3 AND SUBWOOFER)
C4 BLU
(C217 WITH UK3 AND SUBWOOFER)
RADIO
(WITH UK3)
V00578.0

HARNESS CONNECTOR FACES
C1 BLK C2 BLK
VEHICLE SPEED SENSOR BUFFER
Ct BLK CZ BLK
WIPER MOTOR MODULE
VOW09 1