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 ...

    Instrument Panel Storage
    For vehicles equipped with an instrument panel storage area, it is located above the glove box. Access the storage area by pressing and holding in the driver side of the handle and pull out on the ...

    Driving on Snow or Ice
    Drive carefully when there is snow or ice between the tires and the road, creating less traction or grip. Wet ice can occur at about 0°C (32°F) when freezing rain begins to fall, resulting in ev ...