Chevrolet 70 1969 Series, Руководство по ремонту

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C H ASSIS ELECTRICAL A N D INSTRUMENTS 12-13
M A IN LIGHT SWITCH
Main light switch on instrument panel controls
all lights except the stop light and tell-tale lights.
Light switch assembly is shown in figure 16, and
switch circuit diagram is shown in figure 17. Switch
terminals are blade-type. Connector plug, attached
to wiring harness, engages the blade-type termin­
als on switch. Connector plug can be installed only
in one position. Circuit diagram (fig. 17) is shown
as an aid in checking circuits. A rheostat is incor­
porated in the instrument panel light circuit for
purpose of dimming these lights if desired.
The 25-amp automatic reset type circuit
breaker built into the switch assembly protects
the headlight and parking light circuits. Before
replacing light switch, make sure trouble is in
switch and not elsewhere in the lighting system
by checking circuits with suitable equipment.
S W IT C H R E P L A C E M E N T
Removal
1. Pull wiring harness connector plug off
switch terminals.
2. Pull switch knob out to extreme position,
then press on spring-loaded release button on top
of switch assembly and pull switch knob and rod all
the way out.
3. Use a wide-blade screwdriver to remove
ferrule securing switch to instrument panel, then
remove switch assembly.
Installation
1. Position switch under instrument panel,
with locating lug on switch frame engaging hole
in instrument panel. Thread ferrule into switch
frame and tighten firmly, using a wide blade screw­
driver.
2. Insert switch rod through ferrule and push
Figure 17— Main Light Switch Circuit Diagram
in until spring-loaded latch engages groove near
end of rod.
3. Install wiring harness connector plug on
switch terminals, pressing it firmly into place.
4. Check operation of all lights.
DIM M ER SWITCH
Foot-operated dimmer switch is used to se­
lect headlight high or low beam. Switch is mounted
on left-side of cab flooring and is operative when
headlights are illuminated. Switch terminals are
blade type with connector plug attached to harness.
S W IT C H R E P L A C E M E N T
Removal
Make sure main light switch is pushed all the
way in or placed in "Off" position, then remove
dimmer switch as follows:
Conventional Cab Models. Inside cab, raise
floor mat to gain access to switch. Remove two
screws attaching switch to floor pan and pull wir­
ing connector plug off switch terminals.
Tilt Cab Models. Inside cab, remove two
screws attaching switch to toeboard riser. Tilt
cab and from underneath, pull switch free from
toeboard riser. Pull the wiring connector plug off
switch terminal.
Installation
Conventional Cab Models. Install wiring con­
nector plug on switch terminals. Position switch
on cab floor and attach with two mounting screws.
Place floor mat over switch and wiring connector
plug.
Tilt Cab Models. With cab tilted, install
wiring connector plug on switch terminals. Posi­
tion switch under toeboard riser with the button
portion of switch extending through cab floor.
From inside cab, install two screws to attach
switch to toe-board riser.
STOP LIGHT SWITCH
Either a mechanically-operated or air-oper­
ated stop light switch is used on vehicles covered
by this manual.
M E C H A N I C A L L Y O P E R A T E D T Y P E
The mechanically-operated type switch used
on models equipped with vacuum-hydraulic brakes,
is a plunger or lever type switch. With brake pedal
released, edge of pedal lever holds switch plunger
in, breaking circuit to the stop light. When brake is
applied and pedal lever moves away from switch
plunger, a spring within the switch moves the
CHEVROLET SERIES 70-80 H EAVY DUTY TRUCK S H O P M A N U A L