2007 GMC Yukon Owner's Manual - Page 420

Maintenance When Trailer Towing Your vehicle will need service more often when you're pulling a trailer. See the Maintenance Schedule for more on this. Things that are especially important in trailer operation are automatic transmission fluid (don't overfill), engine oil, axle lubricant, belts, cooling system and brake system. Each of these is covered in this manual, and the Index will help you find them quickly. If you're trailering, it's a good idea to review these sections before you start your trip. Check periodically to see that all hitch nuts and bolts are tight. 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 Trailer Wiring Harness Your vehicle is equipped with the following wiring harnesses for towing a trailer. Brown: Taillamps White: Ground Light Green: Back-up Lamps Red: Battery Feed* Dark Blue: Trailer Brake* *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. 420