Trailer Connections (T7/T8 Models Only) - GMC T-Series 2007 Owner's Manual

Trailer Connections
(T7/T8 Models Only)
If your vehicle has these trailer connections, they
are located at the rear of the cab for a tractor
and at the rear of the chassis when towing
a trailer. There will be an air connection and
an electrical connection.
Be sure that the couplings to the trailer are made
correctly.
Air Connections
If you are not connecting the trailer air line
connections to another piece of equipment,
be sure to replace their protective caps.
Electrical Connections
This system is a seven-wire cable that will connect
to the trailer, supplying power to the trailer's
lighting system. When not in use, it is stored
in the trailer air-hose storage bracket.
Heavy-Duty Trailer Wiring Package
Your vehicle may have an eight-wire trailer towing
harness. This harness, with a seven-pin universal
heavy-duty trailer connector, is attached to a
bracket on the platform hitch.
The Center High-Mounted Stoplamp (CHMSL)
wire is tied next to the trailer wiring harness for use
with a trailer.
The eight-wire harness contains the following
trailer circuits:
•
Yellow: Left Stop/Turn Signal
•
Dark Green: Right Stop/Turn Signal
•
Brown: Taillamps
•
White: Ground
•
Light Green: Back-up Lamps
•
Light Blue: CHMSL
•
Red: Battery Feed
•
Dark Blue: Trailer Brake
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