GMC 1982 Light Duty Truck Service Manual page 298

3B4-10 STEERING COLUMNS
F ig . 3 B 4 - 9 - C h e c k in g F u s e s o n F u se B lo c k
TURN SIG N AL D IA G N O S IS C AND K SERIES
Figs. 3B4-9 Through 3B4-16
When a complaint is made involving the turn signal
system, it must first be determined whether the problem is
mechanical o,r electrical. If mechanical, the switch itself is
at fault and must be repaired or replaced. If electrical, J-
23980 should be used to determine whether the switch, or
the chassis wiring is in need of repair or replacement.
This diagnostic procedure has been designed to guide
the mechanic through the proper diagnosis and repair of the
turn signal system. The service section is to be used where
assembly a n d /o r disassembly procedures are required. The
wiring diagram, found in Section 12, should be used to
trouble shoot the chassis and body wiring after the problem
has been isolated.
The nature of the customer complaint will generally
point to the problem area.
Electrical
C h a s s i s E le c tric a l
The most common turn signal system problems are
generally electrical and may easily, be fixed by the
fuses, bulbs, or flashers .
replacement of
First make these checks and replace any non-operative
components.
Check fuses
1. (Figure 3B4-9). Replace if blown. If
new fuse blows, replace flasher in system. (There are 2
flashers in the signal switch system. The hazard warning
flasher and turn signal flasher are located on the fuse block.
2. Check for secure connection at the chassis to switch
connector. This is the harmonica connector on the column
(Figure 3B4-10). Secure if loose. Check all individual wire
terminals for proper seating in the connector bodies.
Terminals should be locked in place.
3. Depress hazard warning button and check all lights
in signal switch system. Replace any which do not work.
F ig . 3 B 4 - 1 0 - - C h e c k in g H a r m o n ic a C o n n e c to r o n C o lu m n
all
If lamps light when hazard warning is depressed, but
flashing does not occur, replace hazard warning flasher. (On
fuse block) (Figure 3B4-11).
all
4. If directional lamps light when lane change or
turn indicator is actuated, but no flashing occurs, replace
the turn signal flasher.
The above four steps will, in most cases, cure the
common signal switch system troubles. If the system is still
not operating correctly, use J-23980 to determine whether
the chassis wiring or the signal switch itself is at fault.
Mechanical
1. If the customer's complaint indicates the problem
is in the switch, function check as to return from full left
and full right turns.
Actuate the turn lever into a full turn position in either
direction, then turn the steering wheel (motor on - power
steering) at least 1/4 turn in the direction indicated and then
Fig. 3B4-1 1-C hecking Hazard W a rning Flasher