
ELECTRICAL-BODY AND CHASSIS 12-24
1.
Temperature Gauge
2.
Instrument Cluster Lamp
3.
R.H. Directional Indicator
4.
Ammeter Gauge
Fig. 39- Optional Gauge Cluster
5. Fuel Gauge
6. L.H. Directional Indicator
7. Tachometer
8. "Brake" Indicator
9. "Bright" Indicator
10.
Oil Pressure Fitting
11.
Chassis Harness Connector
12.
Clock Assembly
13.
Printed Circuit
NOTE:
Observe carefully the stack up of the
internal parts of the fuel gauge assembly.
5. To install, reverse removal procedure.
CLOCK OR TACHOMETER REPLACEMENT
NOTE:
The tachometer is a self-contained, all
transistor unit requiring very little service
other than keeping the terminal nuts clean and
tight. The unit is not serviceable and must be
replaced, if defective.
1.
Remove instrument cluster as previously described
in this section.
2.
For clock replacement, remove clock set shaft knob
at front of console.
3.
Remove cluster lamps from cover, circuit attaching
screws, and terminal nuts at circuit to gauge attach-
ing points.
4.
Move printed circuit away from gauge and remove
screws retaining
•_
gauge or clock to the cluster
housing.
•5.
Remove unit, from housing and cover plate from
gauge unit.
6/To install, reverse removal procedure.
AMMETER TEMPERATURE AND OIL PRESSURE
GAUGES REPLACEMENT
1.
Remove instrument cluster as previously described
iii this section.
2.
Remove instrument lamps, attaching screws or nuts
and wiring connections as required.
3.
Remove gauge assembly backing plate retaining
screws and remove gauge assembly from cluster
housing.
4.
Remove terminal nuts and/or screws retaining gauge
to the backing plate and separate plate from the
gauge.
•
5. To install, reverse removal procedure.
OIL PRESSURE INDICATOR
If the light does not come on when the ignition switch is
turned on, or if the light comes on and remains on after
the engine is started, one or more of the following condi-
tions is indicated:
CHEVROLET CHASSIS SERVICE MANUAL

ELECTRICAL-BODY
AND
CHASSIS
12-26
•
Low oil
pressure
• High engine temperature
• Defective wiring
or
switch
connector from sender
in block above starter
on
and
at
left front
of
distributor
on V-8
Sending Unit Replacement
1.
Disconnect wiring harness
unit terminal (located
L-6 engines
engines).
2.
Remove sender unit using Tool J-21757
or 12
point
socket, replace with
new
unit
and
check operation.
GENERATOR INDICATOR
1.
Ignition
on,
Engine
not
Running
and
Telltale Light
Off.
• Indicator bulb burned out, replace bulb.
• Open circuit
or
loose connection
in the
telltale
light circuit.
2.
telltale Light Stays
on
after Engine
is
Started.
If indicator light does
not go out at
engine idle
speed, refer
to
Charging Systems under Engine
Electrical, Section
6Y.
TEMPERATURE (COOLING SYSTEM) INDICATOR
The temperature indicator circuit consists
of two re-
motely located units, indicator gauge
and
engine sender
unit.
The
indicator gauge, located
in the
instrument
panel, consists
of a
red light which will indicate
an
over-
heated engine condition.
Engine Sender Unit Replacement
1.
Drain engine cooling system
to a
level below unit.
2.
Remove sender unit (located
in the
inlet manifold
near water pump housing
on V-8
engines and
in the
cylinder head near
an
exhaust port
oh L-6
engines)
and replace with new unit.
3.
Refill cooling system
and
check operation
of
unit.
CHEVELLE INSTRUMENTS AND GAUGES
INDEX
Page
General Description
* *
i2-26
Service Operations
12-26
Instrument Panel
12-26
Instrument Cluster.
12-26
Fuel Gauge and/or Ammeter
12-27
Clock,
i 12-27
Speedometer
12-27
Page
Speedometer Cable
.
. 12-27
Temperature Gauge
12-29
Oil Pressure Gauge
12-29
Indicator Lights.
. 12-29
Oil Pressure Indicator
12-29
Generator Indicator
. . 12-29
• Temperature Indicator
12-29
GENERAL DESCRIPTION
The Chevelle instrument cluster assembly consists
of:
a speedometer;
a
fuel gauge;
a
generator,
an
engine
tem-
perature and an
oil
pressure indicator lamp, and includes
a clock
on
deluxe models.
On
super sport models,
am-
meter, coolant temperature
and oil
pressure gauges
re-
place
the
appropriate indicator lights. Except
for the
speedometer,
all of the
indicator lamps, instruments
and
gauges
of
these clusters may
be
serviced without remov-
ing
the
instrument cluster assembly from
the
vehicle.
In addition
to the
instrument indicator lamps,
a
brake
warning lamp
is
included
in the
cluster
as
standard
equipment.
The
indicator
is
connected
to the
parking
brake
and
brake pressure differential switches
and
serves
a
dual function.
It
lights when the parking brake
is applied
and
also when
the
brake pedal
is
applied,
if a
malfunction should occur
in the
brake system
due to a
loss
of
hydraulic pressure. Servicing
of the
hydraulic
pressure differential switch
is
covered
in
Section
5 of
this manual.
Regular maintenance
is not
required on the instrument
cjLuster
or its
components other than maintaining dean
and tight electrical connections, replacing defective parts
and keeping
the
speedometer cable properly lubricated.
SERVICE OPERATIONS
INSTRUMENT PANEL ASSEMBLY
INSTRUMENT CLUSTER (Figs.
41
thru
44)
Removal
1.
Disconnect battery ground cable.
2.
Remove steering coupling bolt and disconnect steer-
ing shaft from coupling.
3.
Loosen mast jacket lower clamp.
4.
Remove
air
conditioning center distributor duct
(if
so equipped).
5. Remove radio rear support bracket screw.
6. Remove mast jacket upper support clamp and retain-
ing bolts from lower support (refer
to
Section
9,
Steering).
CAUTION: Cover mast jacket
and
parl
brake handle with
a
suitable material
to
prevc
scratching.
7.
Disconnect speedometer cable
at
rear
of
cluster
housing
and
speed warning control knob
at
panel
(if
so equipped).
8. Remove instrument panel retaining screws (nine
upper and five lower).
.
9. Working under the console remove four lower retain-
ing screws from instrument cluster housing.
10.
Pull instrument panel assembly from console and
lay
forward on mast jacket.
11.
Disconnect wiring harness, cluster lamps and wiring
CHEVROLET CHASSIS SERVICE MANUAL

ELECTRICAL-BODY AND CHASSIS 12-29
Fig.
43b - Speed Warning Device
TEMPERATURE AND/OR OIL PRESSURE
GAUGE
1.
Disconnect battery ground cable.
2.
Remove ash tray and ash tray retainer.
3.
Disconnect A/C hose from the distributor duct.
4.
Disconnect wiring connectors and lamp bulbs from
rear of gauge.
5. Disconnect oil pressure pipe fitting from rear of oil
pressure gauge.
6. Remove (3) screws retaining gauge assembly to
cluster cover and disengage unit from cover.
7. Remove (4) retaining nuts and remove gauge from
template.
8. To install, reverse removal procedure.
INDICATOR LIGHT REPLACEMENT
To replace any indicator or cluster bulb, unsnap the
proper socket from rear of instrument cluster, remove
and replace bulb, and reinsert unit into rear of cluster
housing.
OIL PRESSURE INDICATOR
If the light does not come on when the ignition switch is
turned on, or if the light comes on and remains on after
the engine is started, one or more the following condi-
tions is indicated:
• Low oil pressure
• Defective wiring or switch
• High engine temperature
Switch Replacement
1.
Disconnect wiring harness connector from sender
unit terminal (located in block above starter on L-6
engines and at left front of distributor on V-8
engines).
2.
Remove sender unit using Tool J-21757, replace with
new unit, and check operation.
GENERATOR INDICATOR
Ignition on, Engine not Running and
Telltale Light Off
1.
Indicator bulb burned out, replace bulb.
2.
Open circuit or loose connection in the telltale light
circuit.
Telltale Light Stays on after Engine is Started
If indicator light does not go out at engine idle speed,
refer to' Charging Systems under Engine Electrical,
Section 6Y.
TEMPERATURE
(COOLING
SYSTEM)
INDICATOR
The temperature indicator circuit, consists of two re-
motely located units, indicator gauge and engine sender
unit. The indicator gauge on all models uses a single
red light to indicate an overheated engine condition.
Engine Sender Unit Replacement
1.
Drain engine cooling system to a level below unit.
2.
Remove sender unit (located in the inlet manifold
near water pump housing on V-8 engines and in the
cylinder head near an exhaust port on L-6 engines)
and replace with new unit.
3.
Refill cooling system and check operation of unit.
CHEVROLET CHASSIS SERVICE MANUAL

ELECTRICAL-BODY AND CHASSIS 12-34
5. To replace, reverse the removal procedure.
SPEEDOMETER REPLACEMENT
1.
Remove instrument cluster as previously described
in this section.
2.
Remove clock set shaft knob.
3.
Remove eight screws securing cluster housing to
bezel trim panel. Separate parts carefully observing
stack up of parts.
4.
Remove two screws securing speedometer head to
rear of cluster housing.
NOTE:
Servicing of the speedometer head
should be performed by an authorized AC Speed-
ometer Service Station.
5. To install, reverse the removal procedure..
SPEEDOMETER CABLE
Replacement or Lubricatibn
1.
Disconnect the speedometer cable from the speed-
ometer head. Remove the old cable by pulling it out
from speedometer end of conduit.
NOTE:
If old cable is broken it may be neces-
sary to remove lower piece from transmission
end of conduit.
2.
Lubricate the lower 3/4 of cable with speedometer
cable lubricant and push the cable into the conduit.
Connect the upper end to the speedometer head and
road test vehicle for proper speedometer operation.
INDICATOR LIGHT REPLACEMENT
To replace any indicator or cluster bulb, unsnap the
proper socket from rear of instrument cluster, remove
and replace bulb, and reinsert unit into rear of cluster
housing.
OIL PRESSURE INDICATOR
If the light does not come on when the ignition switch
is turned on, or if the light comes on and remains on
after the engine is started, one or more of the following
conditions is indicated:
• Low oil pressure
• High engine temperature
• Defective wiring or switch
Switch Replacement
1.
Disconnect wiring harness connector from sender
unit terminal (located in block above starter on
L-6 engines and at left front of distributor on V-8
engines).
2.
Remove sender unit, replace with new unit, and
; check operation.
GENERATOR INDICATOR
1.
Ignition on, engine not running and telltale light off.
a. Indicator bulb burned out, replace bulb.
b.
Open circuit or loose connection in the telltale
light circuit.
2.
Telltale light stays on after engine is started.
a. If indicator light does not go out at engine idle
speed, refer to Charging Systems under Engine
Electrical, Section 6Y.
TEMPERATURE (COOLING SYSTEM) INDICATOR
The temperature indicator circuit consists of two re-
motely located units, indicator gauge and engine sender
unit. The indicator gauge on all models uses a single
red light to indicate an overheated engine condition.
Engine Sender Unit Replacement
1.
Drain engine cooling system to a level below unit.
2.
Remove sender unit (located in the inlet manifold
near water pump housing on V-8 engines and in the
cylinder head near an exhaust port on L-6 engines)
and replace with new unit.
3.
Refill cooling system and check operation of unit.
CORVETTE INSTRUMENTS AND GAUGES
INDEX
Page
General Description ., 12-34
Service Operations . 12-35
Instrument Cluster ., 12-35
Fuel Gauge 12-35
Speedometer/Tachometer Service. 12-35
Temperature Gauge 12-35
Ammeter/Oil Pressure Gauges 12-35
GENERAL DESCRIPTION
All Corvette instruments and gauges are conveniently
located in the dash-mounted cluster. The entire cluster
is removable to permit servicing of the various instru-
ments and gauges. The indicator and cluster illuminating
bulbs may be replaced without removing the cluster from
the panel.
Regular maintenance is not required on the instrument
cluster or its components other than maintaining clean
and keeping the speedometer and tachometer cables
properly lubricated.
CHEVROLET CHASSIS SERVICE MANUAL

ELECTRICAL-BODY AND CHASSIS 12-37
Fig.
50 - Instrument Cluster Installation — Camaro
FUEL GAUGE REPLACEMENT
1.
Remove instrument cluster assembly as previously
described.
2.
Remove cluster lamps from gauge cover plate,
ground screw and terminal nuts attaching printed
circuit to fuel gauge.
3.
Remove three screws retaining gauge assembly to
cluster housing.
4.
Carefully move printed circuit away from gauge and
remove gauge assembly from cluster housing.
5. Remove terminal nuts securing gauge to cover plate,
and detach gauge unit.
6. To install, reverse removal procedure.
TACHOMETER
NOTE:
The tachometer is a self-contained, all
transistor unit requiring very little service
other than keeping the terminal nuts clean and
tight. The unit is not serviceable and must be
replaced, if defective.
1.
Remove instrument cluster as previously described
in this section.
2.
Remove cluster lamps from rear of gauge cover and
disconnect harness wiring connections from gauge
terminals.
3.
Remove three screws retaining gauge to cluster
housing.
4.
Move printed circuit away from gauge area and re-
move gauge unit from housing.
5. Remove terminal nuts securing gauge to cover
detach unit.
6. To install, reverse removal procedure.
SEAT SEPARATOR INSTRUMENT CONSOLE
(Fig.
54)
(Fuel,
Ammeter, Temperature, Oil Pressure Gauges,
Low Fuel Warning Unit, and Clock)
1.
Disconnect battery ground cable.
2.
Remove clock shaft knob from face of cluster.
3.
Remove cover retaining screws (4) and cover from
cluster assembly.
NOTE:
Use an alien wrench to remove the two
screws located in the top of the cover below the
instrument console.
4.
Remove four screws retaining gauge mounting plate
to cluster housing.
5. Carefully disengage gauge plate from housing and
disconnect oil pipe and all electrical connections at
rear of gauges.
NOTE:
At this point, with gauge package re-
moval from housing all gauges including the low
fuel warning system may easily be serviced.
6. To install assembly, use reverse of removal
procedure.
OIL PRESSURE INDICATOR
If the light does not come on when the ignition switch
is turned on, or if the light comes on and remains on
after the engine is started, one or more of the following
conditions is indicated.
• Low oil pressure
• Defective wiring or switch
Sending Unit Replacement
1.
Disconnect wiring harness connector from sender
unit terminal (located in block above starter on L-6
engines and at left front of distributor on V-8
engines).
Fig.
51 - Speed Warning Device
CHEVROLET CHASSIS SERVICE MANUAL

ACCESSORIES 15-9
Adjustment- Adjust the bead chain so that it is as tight
as possible without holding the throttle open when the
carburetor is set at its lowest idle throttle position.
When connecting the bead chain (engine stopped) manually
set the fast idle cam at its lowest step and connect the
chain so that it does not hold the idle screw off the cam.
If the chain needs to be cut, cut it three beads beyond the
bead which pulls the linkage.
REGULATOR
Service - A defective regulator, that is one which is not
simply out of adjustment, must be replaced. During re-
placement, check the hoses which connect to the regulator
and replace any which are cracked or deteriorated.
Air Filter
The air filter located in the solenoid cover should be
cleaned and re-oiled at engine oil change intervals.
1.
Snap the solenoid cover off.
2.
Remove the filter and wash it in kerosene or mineral
spirits. Squeeze it dry and wet with SAE 10 engine
oil.
Squeeze out excess oil and reinstall into the
cover.
3.
Attach the cover with neoprene seal to the solenoid
housing. Be certain that the cover fits tightly to the
housing.
One regulator adjustment is possible: Engagement-
Cruising Speed Zeroing (to remove any difference be-
tween engagement and cruising speed).
NOTE:
No regulator adjustment should be
made, however, until the following items have
been checked or serviced:
1.
Bead chain properly adjusted.
2.
All hoses in good condition, properly attached, not
leaking, not pinched or kinked.
3.
Regulator air filter clean and properly oiled.
4.
Electric and vacuum release switches properly
adjusted.
Engagement—Cruising Speed Zeroing
If the cruising speed is lower than the engagement
speed, loosen the orifice tube locknut and turn the tube
outward; if higher, turn the tube inward. Each 1/8 turn
will alter the engagement-cruising speed difference one
mph. Tighten the locknut after adjustment and check the
system operation at 50 mph.
ELECTRICAL SYSTEM CHECK OUT
1.
Check fuse and connector.
2.
Check electric brake switch as follows: Unplug con-
nector at brake switch. Connect ohmmeter at points
A and B on brake switch. The ohmmeter must indi-
cate infinity when the brake pedal is depressed and
continuity when pedal is released. The cruise re-
lease brake switch (electric) is adjusted as is the
standard stop light brake switch. Replace electric
brake switch if needed.
3.
Check engagement switch and connecting wiring as
follows: Unplug push button control connector
(brown, blue, black) at electrical wiring harness con-
nector and perform the following tests. (See Fig-
ure 10)
Test #1
—
Connect ohmmeter between terminal #1 (brown
wire) and terminal #2 (blue wire). Continuity shall be
maintained until switch is depressed all the way in.
Test #2
—
Connect ohmmeter between terminal #1 (brown
wire) and terminal #3 (black). No continuity shall be
shown; however, when the button is depressed halfway,
continuity shall be indicated. When the button is pressed
all the way down, no continuity shall be shown.
Test #3 — Connect ohmmeter between terminal #2 (blue
wire) and terminal #3 (black). Button released, no con-
tinuity; however, when the button is depressed partially
and fully, continuity shall be shown.
4.
Check regulator solenoid coil, low-speed switch, and
wiring harness as follows:
a. Disconnect engagement switch wire harness con-
nector from the main wire harness connector
(brown, blue, and black wires). Connect ohm-
meter
'
between point C (blue wire in main wire
harness) and ground. (Make sure the regulator is
well grounded to chassis.) The ohmmeter should
read 45 ohms ± 2 ohms. If a resistance of
greater value is shown, then disconnect the con-
nector from the regulator and measure the re-
sistance of the blue wire from point C to D. It
should measure 40 ohms. Check the resistance
from point E (vertical bar of terminal forming T)
to ground. It should measure 5 ohms ± 1/4 ohm.
Replace either the wiring harness or solenoid as
needed if greater values are indicated. The black
harness wiring from point F to G should also be
checked for continuity.
ENGAGEMENT SWITCH TEST
BUTTON POSITION
Cruise (released)
Engage (partially depressed)
Trim (fully depressed)
TERMINALS
1 TO 2
closed
Closed
open
1 TO 3
open
closed
open
2 TO 3
open
closed
closed
SERVO AND VACUUM SYSTEM CHECK OUT
To determine the condition of the diaphragm, remove
hoses from power unit and apply 14 inches of vacuum to
either vacuum tube opening (seal the other opening) and
hold in for one minute. The vacuum shall not leak down
more than 5 inches of vacuum in one minute. If leakage
is detected, replace servo. To utilize engine as a vac-
uum source, proceed as follows:
1.
DISCONNECT SERVO $EAD CHAIN and hoses from
servo and connect engine vacuum directly to vacuum
servo fitting (fitting in middle of servo). Seal the
servo unit opening.
2.
Note position of servo diaphragm.
3.
Start engine - the diaphragm should pull in.
4.
Clamp off engine vacuum supply line and check for
leakage. '
The cruise release brake switch (vacuum) and connecting
hoses can likewise be checked using a vacuum pump.
CHEVROLET CHASSIS SERVICE MANUAL