Chevrolet 70 1969 Series, Shop Manual

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CHASSIS ELECTRICAL AND INSTRUMENTS 12-7
Transmission Temperature
Gauge
2 Engine Oil Pressure Gauge
3 Speedometer
4 Tachometer
15 Engine Temperature Gauge
14 13 12
6 Voltmeter
7 Brake Application Air Pressure
8 Main System Air Pressure
9 L .H . Turn Signal
10 Differential Lock Tell-tale
11 Low Oil Tell-tale
12 Water Temperature Tell-tale
13 Low Air Tell-tale
14 R .H . Turn Signal
15 Fuel Gauge
16 Ammeter
Figure 8 — Typical Instrument
instruments, gauges and tell-tale lights for effic­
ient operation of the vehicle. Figure 9 illustrates
a typical set of instrument clusters, although the
instruments, gauges and tell-tale lights may vary
due to different truck models, depending upon the
size of the vehicle and the equipment used.
Wiring harness connections are made through
multiple plug and receptacle type connectors. A
locating key on harness receptacle engages a slot
in cluster plug to assure correct installation.
Electrical circuits to tell-tale lights, instru­
ment lights, and electrical gauges are printed on
back of instrument case. Each printed circuit
starts and terminates at a terminal post. Each
instrument and tell-tale light bulb is a miniature
base bulb, installed in a plastic holder which locks
into the case and makes contact with the printed
circuit.
In the event of a visible break in a printed
circuit, it can be repaired by soldering; however,
this work must be performed by a competent elec-
Cluster (Series 8 0 Conv. Cab Models)
trician. If it becomes necessary to replace gauges
or instruments, the case must be disassembled.
The cluster face is attached to the case by eight
screws; the two center screws at top and bottom
also attach the retaining clips. Tell-tale and in­
strument light bulbs can be replaced by removing
the bulb holder from the back of the case.
Each cluster is retained in panel by four
spring retaining clips, two at top and two at bot­
tom. Holes are provided in instrument panel to
permit using hooked tool (J-7900) to depress clips
and release cluster from panel. To remove cluster,
maintain a slight pressure on cluster from back
side while releasing the two lower retaining clips,
then release the two upper clips. Use of tool is
shown in figure 10.
C A U T IO N : Do not try to force bent end of tool
too far into opening; this will require more lever­
age to depress the clip and may deform the panel
opening. Do not pry under edges of cluster at front
side of panel; this could damage the bakelite case.
CHEVROLET SERIES 70 -80 H EAVY DUTY TRUCK SH O P M A N U A L