GMC 1982 Light Duty Truck Service Manual page 303

CONDITION
Turn signal lights flash
very slowly
Hazard signal lights will
not flash — turn signal
functions normally
S IG N A L SW IT C H D IA G N O S IS
POSSIBLE CAUSE
A. Inoperative turn
signal flasher
B. System charging
voltage low
C. High resistance ground
at light sockets
D. Loose chassis to
column connection
E. Disconnect column
to chassis connector.
Connect new switch
into system without
removing old. Operate
switch by hand.
If flashing occurs
at normal rate, the
signal switch is
defective.
F. If the flashing rate is
still extremely slow,
check chassis wiring
harness from the
connector to light
sockets for grounds,
high resistance points,
etc.
A. Blown fuse
B. Inoperative hazard
warning flasher
C. Loose chassis to
column connection
D. Disconnect column to
chassis connector.
Connect new switch
into system without
removing old. Depress
the hazard warning
button and observe
the hazard warning
lights. If they now
work normally, the
turn signal switch
is defective.
E. If the lights do not
flash, check wiring
harness " K " lead
(brown) for open
between hazard
flasher and harmonica
connector. If open,
fuse block is defective.
Fig. 3B4-16--Turn Signal S w itch Diagnosis Chart D
STEERING COLUMNS
CORRECTION
Replace turn signal
flasher
B. I ncrease voltage to
specified. See Sec. 6Y
Repair high resistance
C.
grounds at light
sockets
Connect securely and
D.
check operation
Replace signal switch
E.
F. Locate and repair
as required.
Use manual as guide.
See Section 12
A. Replace fuse and
check operation
B. Replace hazard
warning flasher
C. Connect securely and
check operation
D. Replace the turn
signal switch
E. Replace fuse block
(See Sec. 12)
3B4-15