
• • ^ ^ ^ INSTRUMENT PANEL AND GAUGES 8E - 1
CONTENTS
page
CLUSTER AND GAUGE SERVICE PROCEDURES . 12
CLUSTER AND GAUGE TEST PROCEDURES .. i
GENERAL INFORMATION . 1
page
MESSAGE CENTER-DIESEL ENGINE ........ 4
MESSAGE CENTER-GAS ENGINE .......... 3
SWITCH
AND PANEL COMPONENT SERVICE . 16
GENERAL
INFORMATION
INDEX
page
Generator
Indicating
System
2
Distance
Sensor
2
Electronic
Digital
Clock
3
Fuel
Level
Indicating
System
1
page
Malfunction
Indicator
(Check
Engine)
3
Oil
Pressure
Warning
Lamp
................. 2
Speedometer/Odometer
System
2
Temperature
and Oil
Indicating
System
......... 2
D-body trucks have an instrument cluster which
includes gauges for fuel level, coolant temperature,
oil pressure, and charging system voltage (Fig. 1).
When the ignition switch is in the OFF position all
the gauges will show a reading except the voltage gauge. However, the readings are only accurate
when the ignition switch is in the ON position.
The cluster also includes warning lamps for:
• seat belt warning
• low oil pressure
• high beam
• left and right turn signals
• check engine. J908E-66
Fig.
11nstrument
Cluster
FUEL LEVEL INDICATING SYSTEM (FIG. 2)
A hinged float arm in the fuel tank raises or lowers
depending on the fuel level. The float arm contacts a
variable resistor in the gauge sending unit. This pro
vides a change of resistance in the fuel gauge circuit
with any up or down movement of the float. This sender
resistance is shown as fuel level on the gauge. Resistance is greatest when the fuel level in the
tank is low and the float arm drops. With high resis
tance current flow is low and consequently positions
the instrument panel gauge pointer to low.
Resistance in the circuit is at a minimum when the
tank is full and the float arm is raised. With resis
tance at a minimum, current flow is high registering
full on the instrument panel gauge.
12
VOLTS
TO
GAUGE
IP
FUEL
TANK
SENDING
UNIT
FLOAT
SENDING
UNIT
1:
1
j
^
fCONNECTOR
!g|yj-»—
FUEL
GAUGE
FUEL
TANK
J098E-47
Fig.
2
Fuel
Level
Indicating
System
INSTRUMENT PANEL AND GAUGES

8E
- 2
INSTRUMENT PANEL
AND
GAUGES
•
TEMPERATURE AND
OIL
INDICATING SYSTEM
(FIG.
3) The operation of the temperature and oil pressure
indicating systems are identical. In the temperature
system the sending unit resistance varies in direct
relationship to the temperature of the coolant. When the engine is cold, the resistance of the tem
perature sending unit is high and a cold temperature
will be indicated on the gauge. When the engine is hot, the resistance of the tem
perature sending unit is low and a hot temperature
will be indicated on the gauge. In the oil pressure indicating system the sending
unit resistance is actuated by a diaphragm as the oil
pressure increases or decreases. Low oil pressure causes high resistance. High pressure causes low re
sistance. 12
VOLTS
TO
GAUGE
TEMPERATURE/
OIL GAUGE
TEMPERATURE/OIL SENDING
UNIT
J908E-48
Fig. 3 Temperature/Oil indicating System
OIL
PRESSURE
WARNING LAMP
The oil pressure warning switch, mounted on the
engine, is controlled by engine oil pressure. When engine oil pressure is normal, the switch is
held in the OFF or OPEN position. This stops cur
rent from flowing to the oil pressure warning lamp
on instrument panel. When the engine oil pressure is low, the switch is
in the ON or CLOSED position. This allows current
to flow to the oil pressure warning lamp in the in strument cluster causing the warning lamp to illumi
nate.
GENERATOR
INDICATING
SYSTEM
(FIG. 4)
The voltmeter gauge senses the voltage of the elec
trical system.
VOLTAGE
/*
GAUGE
P/
J908E-49 Fig. 4 Generator Indicating System
SPEEDOMETER/ODOMETER SYSTEM
The speedometer/odometer system consists of an
electric speedometer and pushbutton reset odometer
mounted in the cluster. The system also includes the
wire harness from the cluster to the distance sensor at the transmission, and the adapter and pinion in
the transmission. The speedometer/odometer has the same appearance as a conventional version but it
eliminates the cable-driven mechanical system. A signal is sent from a transmission mounted distance
sensor to the speedometer/odometer circuitry through
the wiring harness. By eliminating the speedometer cable, instrument cluster service and removal is im
proved. Refer to Group 21 - Transmission for select ing the proper pinion, and selecting and indexing the
proper adapter.
DISTANCE
SENSOR
DISTANCE SENSOR TEST For testing of the distance sensor and related com
ponents refer to the Vehicle Diagnostics Test Proce dure Manual.
DISTANCE SENSOR REMOVAL AND INSTALLATION (1) Remove harness connector from sensor. Be sure
weather seal stays on harness connector. (2) Remove sensor by loosening sensor coupling
nut from the pinion gear adapter until sensor is free (Fig. 5).
(3) To install the sensor, reverse the removal pro
cedures. Tighten coupling nut to 17 N»m (150 in. lbs.)

8E
- 12
INSTRUMENT PANEL
AND
GAUGES
•
CLUSTER AND GAUGE
SERVICE
PROCEDURES
INDEX
page
Cluster Bezel
12
Cluster
Mask
and
Lens
12
Fuel Gauge
13
Instrument
Cluster Assembly
12
Lamp Bulb Replacement—Message Center
..... 15
CLUSTER
BEZEL
REMOVAL
(1) Disconnect negative cable from battery.
(2) Tape
or
cover steering column
to
prevent dam
age
to
paint.
(3) Remove
2
screws and remove map lamp.
CAUTION:
Map
lamp must
be
removed
to
prevent
damage
to
instrument panel.
(4) Remove
6
screws which attach cluster bezel
to
base panel (Fig.
1).
Make sure
the
screw below
the
Heater-A/C control
is
removed.
(5)
Place column shift lever
in
Position
"1".
(6) Remove bezel
by
pulling
top
edge rearward
to
clear brow. Disengage attaching clips around bottom
of bezel
and
complete removal
of
bezel.
(7)
If
bezel
is
equipped with
a
four wheel drive
in
dicator, remove bulb socket
as
bezel
is
removed.
(8) Disconnect message center wires.
INSTRUMENT
CLUSTER BEZEL
J938E-51
Fig.
1 instrument
Cluster
Bezel
INSTALLATION
(1) Connect bulb socket
for
four wheel drive indi
cator
if
equipped.
(2)
Connect message center wires.
(3) Engage attaching clips around bottom
of
bezel,
roll bezel into position.
(4) Install
6
mounting screws. page
Lamp Bulbs
. . 15
Printed
Circuit
Board
13
PRND21
Indicator
. 15
Specifications
15
Speedometer/Odometer
14
(5)
Install map lamp.
(6) Remove tape from steering column.
(7) Connect negative cable
to
battery.
CLUSTER
MASK AND LENS REMOVAL
(1) Disconnect negative cable from battery.
(2) Remove cluster bezel.
(3) Remove
8
screws holding mask
and
lens.
(4) Remove mask
and
lens.
INSTALLATION
(1) Position mask
and
lens.
(2) Install
8
screws.
(3) Install cluster bezel.
(4) Connect negative cable
to
battery.
INSTRUMENT CLUSTER ASSEMBLY
(Fig.
2)
REMOVAL
(1) Disconnect negative cable from battery.
(2) Tape
or
cover steering column
to
prevent dam
age
to
paint.
(3) Remove bezel.
(4) Remove lower steering column cover
4
screws.
(5)
Spread upper steering column cover
out of
the
locking tangs
and
slide downward. (6) Disconnect PRND21 actuator cable from steer
ing column
if
equipped.
(7) Loosen heater
and
A/C control. Pull rearward
to clear forward mount
on
cluster housing.
(8) Remove
6
screws that retain cluster. Pull clus
ter rearward
and
disconnect
2
large connectors.
(9) Remove cluster.
INSTALLATION
(1) Connect
2
large connectors
to
cluster.
(2) Position cluster
to
instrument panel and install
6 retaining screws.
(3) Install heater A/C control.
(4) Connect PRND21 actuator
to
steering column
if
equipped.
(5)
Position upper steering column cover
and
slide
upward until tangs snap into place.

8E
- 14
INSTRUMENT
PANEL
AND
GAUGES
•
VOLTAGE
GAUGE
Fig. 3 instrument Cluster Printed Circuit Board
SPEEDOMETER OIL
PRESSURE
GAUGE
TEMPERATURE GAUGE
FUEL
GAUGE
Fig. 4 Cluster With Mask Removed
J908E-69
(4)
Remove gauge mounting screws.
(5) Pull gauge rearward to remove.
For Installation, reverse Removal procedures.
SPEEDOMETER/ODOMETER
It is not necessary to remove instrument clus
ter from vehicle for speedometer replacement. When removing speedometer (Fig. 4) from cluster,
gauge must be pulled straight out, not twisted, or
damage to gauge pin and/or printed circuit board
may result. (1) Disconnect negative cable from battery.
(2) Remove bezel. Refer to Cluster Bezel Removal.
(3) Remove cluster mask and lens. Refer to Cluster
Mask and Lens Removal. (4) Remove mounting screws retaining speedome
ter/odometer to housing.
(5) Pull speedometer/odometer rearward to remove.
For Installation, reverse Removal procedures.