Rear Running Lamps And Marker Lamps; Rear Park Lamps; Rear Turn, Stop And Hazard Systems; Backup Lamp System - GMC G Service Manual

M Install or Connect (Figures 16 and 17)
1. Bulb (33) to the lamp (31).
2. Side marker lamp (31) into the fender (30).
3. Two screws (32).
The rear lighting systems contain the circuits for the run­
ning, park, turn, stop and license lamps. One bulb may
function for more than one circuit. The harness for the rear
lighting systems starts at the fuse block, goes to the various
switches and then back along the left frame to the various
lamps (figures 2, 18 and 19).
REAR RUNNING LAMPS AND
MARKER LAMPS
This circuit starts at the lamp switch. The lamps will be
on when the lamp switch is in the first and second detents.
The front park lamps and front marker lamps will also be on
when the lamp switch is in the first detent (figure 2).

REAR PARK LAMPS

These lamps will be on when the lamp switch is in the
first detent. The front park lamps will also be on. The side
marker lamps will also be on (figure 2).
REAR LIGHTI
CHASSIS ELECTRICAL 8B-19
30. Front Fender
31. Side Marker Lamp
32. Screw
34. Nut
Figure 17 — G-Van Front Side Marker Lamp
G SYSTEMS
REAR TURN, STOP AND HAZARD
SYSTEMS
These three systems use the same bulb in the rear
lamps. When the rear turn system is turned on, a thermal
oscillator is turned on, which causes the system to flash.
The front park lamps are also a part of the turn system .
The stop lamp system is turned on by a brake switch
closing. The two rear bright lamps are then turned on (fig­
ure 19).
The hazard system is turned on by the hazard switch.
The hazard system thermal oscillator is then turned on
which causes the front park lamps and the rear bright lamps
to flash (figure 18).

BACKUP LAMP SYSTEM

This circuit is turned on when the transmission is shifted
into reverse. The backup switch is closed, thus turning on
the backup lamps. The backup lamps are located in the
rear lamp assemblies (figure 20).
F-00871