GMC 1986 P-Truck Service Manual page 246

DIAGNOSIS OF THE STEERING COLUMN (CONT.)
PROBLEM
Front Or Rear Turn
Signal Lights Are
Not Flashing (Cont.)
6. If vehicle lights do not operate, check
Stop Light Not On
When Turn Indicated
2. Loose column to chassis connection.
3. Disconnect column to chassis connec­
4. If brake lights do not work, check con­
Turn Indicator Panel
Lights Not Flashing
2. High resistance to ground at the bulb
3. Opens, grounds in wiring harness from
Turn Signal Lights
1. Inoperative turn signal flasher.
Flash Very Slowly 2. System charging voltage low.
3. High resistance ground at light sock­
4. Loose chassis to column connection.
5. Disconnect column to chassis connec­
6. If the flashing rate is still extremely
POSSIBLE CAUSE
5. Disconnect column to the chassis con­
nector. Connect a new switch into the
system and operate the switch by
hand. If turn signal lights are now on
and flash, the turn signal switch is in­
operative.
the chassis wiring harness to light
sockets for opens, grounds, etc.
1. Burned out fuse.
tor. Connect new switch into system
without removing old. Operate switch
by hand, if brake lights work with
switch in the turn position, signal
switch is faulty.
nector to stop light, the sockets for
grounds, opens, etc.
1. Burned out bulbs.
socket.
the front turn signal bulb socket to the
indicator lights.
ets.
tor. Connect new switch into system
without removing old. Operate switch
by hand. If flashing occurs at normal
rate, the signal switch is faulty.
slow, check chassis wiring harness
from the connector to the light sockets
for high resistance.
STEERING COLUMN 3B4-7
CORRECTION
5. Replace the turn signal switch.
6. Repair the chassis wiring.
1. Replace fuse and check operation.
2. Connect securely and check opera­
tion.
3. Replace the signal switch.
4. Repair connector to stop lights cir­
cuits.
1. Replace the bulbs.
2. Replace the socket.
3. Locate and repair as required.
1. Replace the turn signal flasher.
2. Increase voltage to specifications.
Refer to (SEC. 6D ENGINE ELECTRI­
CAL) in this manual.
3. Repair high resistance grounds at the
light sockets.
4. Connect securely and check opera­
tion.
5. Replace signal switch.
6. Locate and repair as required. Refer
to SEC. 8B (CHASSIS ELECTRICAL)
in this manual.