Trailer Wiring Harness

Basic Trailer Wiring

The trailer wiring harness, with a seven-pin connector, is located at the rear of the vehicle and is tied to the vehicle's frame. The harness connector can be plugged into a seven-pin universal heavy-duty trailer connector available through your dealer.

The seven-wire harness contains the following trailer circuits:
• Yellow: Left Stop/Turn Signal
• Dark Green: Right Stop/Turn Signal
• Brown: Taillamps
• Black: Ground
• Light Green: Back-up Lamps
• Red/Black: Battery Feed
• Dark Blue: Trailer Brake*

*The fuse for this circuit is installed in the underhood electrical center, but the wires are not connected.

They should be connected by your dealer or a qualified service center.

If the back-up lamp circuit is not functional, contact your dealer.

If a remote (non-vehicle) battery is being charged, press the Tow/Haul mode switch located on the center console near the climate controls.

This will boost the vehicle system voltage and properly charge the battery. If the trailer is too light for Tow/Haul mode, turn on the headlamps (non-HID only) as a second way to boost the vehicle system and charge the battery.

    See also:

    Vehicle Overview
    GMC redesigned its full-size vans for the first time in seven years for the 2003 model year. The 2003 Savanas got upgraded powertrains, fresh features and an updated appearance. Three industry fir ...

    Care of the CD Player
    Do not add any label to a CD; it could get caught in the CD player. If a CD is recorded on a personal computer and a description label is needed, try labeling the top of the recorded CD with a markin ...

    Vehicles without Navigation System
    The RVC system displays a view of the area behind the vehicle. When the vehicle is on and shifted into R (Reverse) the video image appears on the inside rearview mirror. The video image disappears aft ...