fuse chart GMC SIERRA 1999 Owner's Manual

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4-60 Trailer Wiring Harness
A. Light-Duty Wiring Harness
B. Additional Heavy
-Duty Wiring
C. Tie Straps
An eight
-wire harness is stored under the rear end of
your vehicle. Five wires (A) are located between the rear
bumper and the spare tire, near the center. This wiring
harness is tie
-strapped to the taillamp and stoplamp
harness. Three wires (B) (light gauge white, blue and
orange) are located at the rear left hand frame rail.This harness has a 30
-amp battery feed wire and no
connector, and should be wired by a qualified electrical
technician. After choosing an aftermarket mating
connector pair, have the technician attach one connector
to the eight
-wire trailer harness and the other connector
to the wiring harness on the trailer. Be sure that the
wiring harness on the trailer is strapped to the trailer's
frame and leave it loose enough so that the wiring
doesn't bend or break, but not so loose that it drags on
the ground. The technician can use the following color
code chart when connecting the wiring harness to
your trailer.

Brown: Rear Lamps

Yellow: Left Stoplamp and Turn Signal

Dark Green: Right Stoplamp and Turn Signal

White (Heavy Gauge): Ground

Light Green: Back
-up Lamps

White (Light Gauge): Center High
-Mounted
Stop Lamp

Blue: Auxiliary/Electric Trailer Brake Circuit

Orange: Fused Auxiliary Circuit
Store the harness in its original place. Wrap the harness
together and tie it neatly so it won't be damaged.