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 12-35
SERVICE OPERATIONS
INSTRUMENT CLUSTER
REMOVAL AND INSTALLATION (Fig. 49)
1.
Remove mast jacket assembly. Refer to Section 9
for removal procedures.
2.
Disconnect tachometer drive cable at distributor.
3.
Disconnect the headlamp panel control switch from
instrument cluster.
4.
Remove lighting switch as outlined in this section.
10 10-A 1112 13
14
15 16 17 18 19
Fig.
49- Instrument Cluster Connections
1.
Cluster Illuminating
Bulbs
2.
Direction Signal Indicator
Bulb L.H.
3. Direction Signal Indicator
BulbR.H.
4.
Headlamp Actuating Motor
Indicator
5. Headlamp Hi Beam
Indicator
6. Parking Brake Alarm
Indicator
7. Ground Lead Attaching
Point
8. Temperature Indicator
"1"
Terminal
9.
10.
10A.
11.
12.
13.
14.
]5.
16.
17.
18.
19.
20.
21.
Temperature Indicator "S"
Terminal
Ignition Switch Receptacle
ignition Switch Illuminating
Bulb
Oil Pressure Indicator
Tachometer
Lighter Receptacle
Trip Odometer
Wiper Switch Receptacle
Speedometer
Ammeter "Gen" Terminal
Ammeter "Battery" Terminal
Lighting Switch Receptacle
Fuel Gauge
"1"
Terminal
Fuel Gauge "S" Terminal
5. Remove the ignition switch. Refer to Section 6Y
for removal procedure. Then disconnect ignition
switch lamp support at instrument panel.
6. Disconnect oil pressure line at oil pressure gauge
then remove the lead wires from ammeter, wiper
switch and cigarette lighter. Disconnect trip odom-
eter at mast jacket support.
7. Remove the instrument cluster-to-dash retaining
screws and pull cluster assembly slightly forward
to obtain clearance for removal of speedometer
cable, tachometer cable, cluster ground wire, fuel
gauge lead wires and remaining indicator and cluster
illuminating lamps.
8. To install cluster in dash panel, reverse removal
procedure.
FUEL GAUGE
The gasoline fuel gauge circuit consists of an electri-
cal indicator in the instrument cluster and a float-
controlled rheostat in the fuel tank.
Since the fuel gauge consists of two remotely located
units and connecting wires, it is sometimes difficult to
determine which unit is at fault when the gauge fails to
operate properly. Cluster removal is necessary to re-
place the fuel gauge.
NOTE:
Be sure to check gas gauge fuse in fuse
panel before attempting to trouble shoot for
inoperative gauge or tank sending unit.
SPEEDOMETER AND/OR TACHOMETER
Removal and Installation
Cluster must be removed from vehicle to service
speedometer head assembly (see Cluster Removal pro-
cedure)
.
With cluster removed from vehicle:
1.
Remove five screws securing cluster back panel to
cluster assembly; separate the parts carefully.
CAUTION: Care must be used to avoid marring
instrument cluster face.
2.
Remove two screws securing speedometer or ta-
chometer head to cluster back panel; carefully re-
move speedometer or tachometer head.
NOTE:
Servicing of speedometer or tachom-
eter head should be performed by an authorized
AC service station.
3.
Reverse above procedure to install speedometer.
Cable Replacement or Lubrication
1.
Disconnect the. cable from the speedometer or ta-
chometer head. Remove the old cable by pulling it
out from speedometer end of conduit.
NOTE:
If old cable is broken it may be nec-
essary to remove lower piece from transmission
or distributor end of conduit as applicable.
2.
Lubricate the lower 3/4 of cable with
AC
speedom-
eter cable lubricant and push the cable into the con-
duit. Connect the upper end to the speedometer or
tachometer head and road test vehicle for proper
operation.
TEMPERATURE GAUGE
The temperature indicator requires very little service
other than testing for malfunctioning and replacing de-
fective units. Cluster must be removed to service tem-
perature gauge.
Do not attempt to repair either the engine unit or the
gauge. When installing new engine unit, do not use
thread compound on unit threads, as this will increase
electrical resistance of unit and cause faulty reading
on gauge.
AMMETER OR OIL PRESSURE GAUGE
The ammeter or oil pressure gauge requires very
little attention other than keeping ammeter terminals
clean and tight. If the oil pressure control line should
become restricted it should be blown out or replaced.
Cluster must be removed to service these gauges.
HftVKI MANUAL
ELECTRICAL-BODY AND CHASSIS 12-38
Fig.
52 - Instrument Cluster Lighting
1
• Cluster Lamp
2.
* High Beam Indicator
3. Oil Pressure Indicator
4.
L.H. Directional Indicator
5. Generator indicator
6. R.H. Directional indicator
7. Temperature Indicator
8. Printed Circuit
9. Chassis Harness Connector
10,
Brake Warning Indicator
2.
Remove sender unit.
3.
Replace with new unit and check operation.
GENERATOR INDICATOR
1.
Ignition on, engine not running and indicator light off:
•Indicator bulb is burned out, replace bulb.
•Open circuit or loose connection in the indicator
light circuit.
2.
Indicator light stays on after engine is started:
•Ti indicator light does not go out at engine idle
speed, refer to Charging System Tests in Section
6Y, Engine Electrical.
TEMPERATURE (COOLING SYSTEM) INDICATOR
The temperature indicator circuit consists of two re-
motely located units, indicator lamp and sending unit.
The "indicator lamp, located in the instrument cluster
CHfVROtEr CHASM SfXVICf
ELECTRICAL-BODY AND CHASSIS 12-40
Fig.
54 - Seat Separator Instrument Console
consists of a single 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 cylinder head near
an exhaust port on L-6 engines and in the inlet mani-
fold near water pump housing on V-8 engines).
3.
Replace unit, refill cooling system and check opera-
tion of unit.
DIRECTIONAL SIGNAL
Directional signal assemblies provide as standard pro-
duction equipment a lane changing feature and hazard
warning system on all model applications. Two different
design switches are used as shown in Figure 55. Major
difference between the two units is that one type has can-
celling and detent springs which are serviceable, other-
wise both units are not repairable and must be replaced
as an assembly in service.
Due to the integral design relationship of the signal
switch and the energy absorbing steering column, refer-
ence should be made to Steering, Section 9 of this manual
whenever any service operations are performed on the
steering column. The directional signal switch replace-
ment procedures covered in this section are intended to
supplement the detail service operations outlined in Sec-
tion 9.
Special note should be taken of the fact that different
signal flasher units are used in Chevrolet models depend-
ent on the number of lamps to be operated. The hazard
warning unit, even though an integral component of the
directional switch assembly, requires the installation of
an additional flasher unit in the fuse panel capable of op-
CHEVROtET 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