1998 GMC Envoy Owner's Manual - Page 211

Trailer Wiring Harness The heavy-duty trailer wiring is an eight-wire harness assembly. The harness is stored under the vehicle, on the driver's side corner frame rear crossmember. The heavy-duty trailer wiring has a 30-amp feed wire with an in-line fuse located by the junct.ion block. See "Fuses and Circuit Breakers" in the Index. The harness does not have a cannector 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. 0 Dark Blue: Use for electric trailer brakes or auxiliary wiring. Red: Use for battery charging; it connects to the starter solenoid. Light Green: Back-up lamps. Brown: Taillamps and parking lamps. Yellow: Left stoplamp and turn signal. Dark Green: Right stoplamp and turn signal. White (Heavy Gage): Ground wire. White (Light Gage): Auxiliary stoplamp. 0 0 0 0 0 0 0 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. 4-52