GMC Sierra 2008 Owner's Manual page 391

*The fuses for these two circuits are installed in the
underhood electrical center, but the wires are not
connected. They should be connected by your dealer
or a qualified service center. The fuse and wire for
the ITBC is factory installed and connected if the
vehicle is equipped with an ITBC. The fuse for the
battery feed is not required if your vehicle has an
auxiliary battery. If your vehicle does not have an
auxiliary battery, have your dealer or authorized
service center install the required fuse.
If you are charging a remote (non-vehicle) battery,
press the tow/haul mode button located at the end
of the shift lever. This will boost the vehicle system
voltage and properly charge the battery. If the trailer
is too light for tow/haul mode, you can turn on the
headlamps as a second way to boost the vehicle
system and charge the battery.
Camper/Fifth-Wheel Trailer Wiring
Package
The seven-wire camper harness is located under
the front edge of the pickup box on the driver's
side of the vehicle, attached to the frame bracket.
A connector will have to be added to the wiring
harness which connects to the camper.
The harness contains the following camper/trailer circuits:
•
Yellow: Left Stop/Turn Signal
•
Dark Green: Right Stop/Turn Signal
•
Brown: Taillamps
•
White: Ground
•
Light Green: Back-up Lamps
•
Red: Battery Feed
•
Dark Blue: Trailer Brake
If your vehicle is equipped with the "Heavy-Duty
Trailering" option, please refer to "Heavy-Duty Trailer
Wiring Package" earlier in this section.
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