Chevrolet 1977 light duty truck Service Manual page 214

C O N D ITIO N
F ro n t o r rear tu rn signal
lights not flashing
Stop light not on when
tu rn indicated
T u rn indicator panel
lights n ot flashing
SIGNAL SWITCH DIAGNOSIS
POSSIBLE CAUSE
A . Burned o u t fuse
Burned o u t or
B.
damaged tu rn signal
bulb
High resistance
C.
connection to ground
at bulb socket
D. Loose chassis to
colum n connector
E. Disconnect colum n to
chassis connector.
C onnect new switch
into system and
operate switch
by hand.
If tu rn signal lights
are now on and
flash, tu rn signal
switch is inoperative.
F. If vehicle lights do
not operate, check
chassis w iring harness
to light sockets fo r
opens, grounds, etc.
Burned o u t fuse
A.
B. Loose colum n to
chassis connection
C. Disconnect colum n to
chassis connector.
C onnect new switch
into system w ith o u t
rem oving old. O perate
switch by hand.
If brake lights w o rk
w ith switch in th e
tu rn position, signal
switch is defective
D.
If brake lights do not
w o rk check connector
to stop light sockets
fo r grounds, opens,
etc.
A .
Burned o u t bulbs
B. High resistance to
ground at bulb socket
C. Opens, grounds in
w irin g harness fro m
fro n t tu rn signal bulb
socket to indicator
I ights
CORRECTION
Replace fuse and
A.
check o p eratio n
Replace bulb
B.
C. Remove o r repair
defective connection
and check o p eration
D. Connect securely and
check operation
E. Replace tu rn signal
switch.
Repair chassis w irin g
F.
as required using
manual as guide
A . Replace fuse and
check operation
B. Connect securely and
check op eratio n
C. Replace signal switch
D.
Repair connector to
stop light circuits
using manual as guide.
A. Replace bulbs
B. Replace socket
C. Locate and repair as
required. Use shop
manual as guide.