Trailer Wiring - GMC G Service Manual

8B-22 CHASSIS ELECTRICAL
Figure 21 — R/V Pickup—Trailering Harness

TRAILER WIRING

R/V-MODELS
There is one type of trailer harness available. Option
UY7 is a heavy duty trailer harness. One portion of the
harness is a 30 amp fused battery feed wire from the
junction block mounted on the cowl. This harness is
routed along the vehicle frame rail to the rear bumper
crossmember. The rest of the trailer harness is spliced
from the rear lamp harness. This harness is Icoated at the
rear of the left frame rail, and is wrapped and bound with
a plastic strap on all pickup models. The harness is
located on the frame crossmember nearest the rear
bumper on the utility vehicle. The wires are taped over the
harness to prevent shorting of the wires.
This option does not include a connector at the end of
the harness, and must be wired after production by a
qualified service person (figures 21 and 22).
The five wires included in the harness are:
1. White — Ground.
Figure 22—R/V Utility Vehicle — Trailing Harness
2. Brown — Tail lamps.
3. Light Green — Back up lamps.
4. Dark Green — Right turn signal, and stop lamp.
5. Yellow — Left turn signal, and stop lamp.
The second wire (the 3 0
also be wired after production. The function of this wire
may vary depending on application. This red wire is taped
to prevent accident grounding which would blow the fuse.
The trailer harness wiring should be attached to the
trailer, and then strapped to the vehicle frame rail in such
a way that enough slack is left in the harness to prevent
bending, binding, or breakage of the wiring. Do not allow
the harness to be so loose, that it drags on the ground.
Tape or strap the trailer portion of the harness (if used) to
the tongue of the trailer. This will prevent the harness from
dragging on the ground.
When the wiring is not being used, wrap the harness
together, and bind it with a tie strap to keep it from being
damaged. Store the harness behind the rear bumper on
the left hand frame rail with a band or tie strap.
G-MODELS
There are two types of trailer harnesses available.
Option UY7 is a heavy duty trailer harness. One portion of
the harness is a amp fused battery feed wire from the
3 0
junction block mounted on the cowl. This harness is
routed along the body side rail to the rear bumper
crossmember. The trailer harness is spliced from the rear
lamp harness. This harness is for the brake/parking
lamps, and an auxiliary power feed. The harness is
located at the rear bumper crossmember, and is wrapped
and bound with a plastic strap to the fuel tank strap. The
wires are taped over the harness to prevent shorting of
the wires.
This option does not include a connector at the end of
the harness, and must be wired after production by a
qualified service person (figure
The five wires included in the harness are:
1. White — Ground.
Brown — Tail lamps.
2 .
Light Green — Back up lamps.
3.
4. Dark Green — Right turn signal and stop lamp.
5. Yellow — Left turn signal, and stop lamp.
A. 30 Amp Battery Feed
B. Trailer Harness
C. Ground
amp fused battery feed) must
2 3 ).
F-05816