2008 GMC Acadia Owner's Manual - Page 313

Trailer Wiring Harness Your vehicle is equipped with the following wiring harness for towing a trailer. *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/retailer or a qualified service center. If the back-up lamp circuit is not functional, contact your dealer/retailer. If you are charging a remote (non-vehicle) battery, 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, you can turn on the headlamps (Non-HID only) as a second way to boost the vehicle system and charge the battery. Basic Trailer Wiring If your vehicle is equipped for heavy duty trailering, 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/retailer. 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* Engine Cooling When Trailer Towing Your cooling system may temporarily overheat during severe operating conditions. See Engine Overheating on page 5-25. 4-41