2001 GMC Savana Van Owner's Manual - Page 234

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, belt, 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. Four-Wire Harness D D D D Light Green: Back-up lamps Brown: Parking lamps Yellow: Left stoplamp and turn signal Dark Green: Right stoplamp and turn signal Three-Wire Harness D Dark Blue: Use for electric trailer brakes (seven-wire harness only) D Orange: Trailer accessory (seven-wire harness only) D White (heavy gage): Ground wire Securely attach the harness to the trailer, then tape or strap it to your vehicle's frame rail. Be sure you leave it loose enough so the wiring doesn't bend or break, but not so loose that it drags on the ground. Store the harness in its original place. Wrap the harness together and tie it neatly so it won't be damaged. Trailer Wiring Harness The optional heavy-duty trailer wiring package is a seven-wire harness assembly. The four-wire portion of the harness assembly is stored under the vehicle, along the driver's side rear corner of the frame rail. The three-wire portion of the harness assembly is stored in a frame pocket under the rear of the vehicle, on the driver's side. The heavy-duty trailer wiring harness has a 30-amp feed wire. Both harnesses come without connectors and should be wired by a qualified electrical technician. The technician can use the following color code chart when connecting the wiring harness to your trailer. 4-42