Chevrolet 70 1969 Series, Shop Manual

Page: 513 / 913

CHASSIS ELECTRICAL A N D INSTRUMENTS 12-14
plunger out to complete the stop light circuit.
Switch terminals are blade type with wiring con­
nections made through a connector plug on wiring
harness. Switch cannot be disassembled; therefore,
if switch becomes inoperative, it must be replaced.
When installing a lever type switch, make sure
lever on switch is located above brake pedal lug,
otherwise switch will not be operative. Also, make
sure wiring connections at switch are fully engaged.
After installing switch, it must be adjusted so
that initial movement of brake pedal, measured at
the pedal pad, will permit switch to close and com­
plete stop light circuit. After adjusting and tight­
ening switch mounting nuts or bolts, visually check
operation of stop light to make sure stop light
comes on when brakes are applied and goes out
when brake pedal is released.
AIR O P E R A T E D T Y P E
The air operated type stop light switch is used
on vehicles equipped with air brakes or I.C .C .
trailer brake controls. Refer to "A IR B R A K E S "
(S E C . 5B) for information pertaining to this switch.
BACK-UP LIGHT SWITCH
The back-up light switch, mounted on the
transmission, is activated by the transmission re­
verse shift rail when the ignition or control switch
is placed in the on position and the transmission
shift lever is in reverse position. If back-up lights
become inoperative, disconnect the wiring harness
connector plug from the switch. Connect both term­
inals in the connector with a jumper wire, then
place the ignition or control switch in the on posi­
tion. If back-up lights operate, replace the switch.
DIRECTIONAL SIGNAL LIGHTS
Directional signal lights are either an integral
part of the stop and taillight assemblies or are
mounted on each side of cab, or in combination.
N O T E : On some models, a combination di­
rectional and side marker lamp (fig. 18) is
mounted on each side of cab.
To replace the side marker lamp bulb, re
move two screws which retain the amber marker
lens to the light assembly, then remove the lens.
Press inward on bulb and turn clockwise to
secure. Place gasket and lens on lamp housing
and attach with two screws.
When ignition or control switch is placed in
" O N " position, 12-volts is supplied through a fuse
to the flasher unit. Placing right-hand directional
signal on (lever in up position) supplies 12-volts
from flasher unit through switch, then to right-
hand signal. The same procedure applies to the
left-hand signal, except that lever is in the down
position and a different set of contacts are engaged
in switch assembly.
On conventional cab models, an arrow at either
side or tell-tale cluster flashes when either the
left or right signal light is illuminated. When turn
is completed, switch lever is automatically return­
ed to " O F F " position by a cancelling cam installed
on steering wheel.
On tilt cab models, a tell-tale light on instru­
ment panel marked "TURN- SIG" flashes when either
the left or right signal light is illuminated. When
turn is completed, switch lever is automatically
returned to " O F F " position by a cancelling cam
installed on steering wheel.
If directional tell-tale on instrument panel
flashes in one position but not the other, check for
the following:
1. Directional lamp bulb burned out.
2. Incorrect directional lamp bulb installed.
3. Defective ground between bulb socket and
mounting.
4. Defective directional control switch assem­
bly.
If directional tell-tale on instrument panel
does not flash in either direction, check for the
following:
1. Burned out fuse on fuse block.
2. Defective flasher or flasher terminals not
properly engaged in junction block.
3. Directional tell-tale bulb on instrument
panel burned out.
4. Short or open circuit. Check indicator
lamp c i r c u i t referring to applicable wiring
diagram.
5. Defective directional control switch as­
sembly.
Figure 18—Directional Signal Light and Side Marker
LENS M O U N T IN G SCREW
CHEVROLET SERIES 70 -80 H EAVY DUTY TRUCK S H O P M A N U A L