ORIGINAL: swartlkk

Search> Wiring for Towing < My post in that thread should cover it for you.

For a digital copy of your owners manual, you can go to https://apps.gmcanada.com/

Trailer Wiring Harness
The light-duty trailer wiring is a six-wire harness assembly. The optional heavy-duty trailer wiring is an eight-wire harness assembly. The harnesses are stored under the vehicle, along the passenger-side frame crossmember on two-door vehicles or on the driver’s side corner frame rear crossmember on four-door vehicles. The heavy-duty trailer wiring is fused in the engine compartment fuse block. See Fuses and Circuit Breakers on page 5-88. Both harnesses have no connector 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.
[ul][*]Dark Blue: Use for electric trailer brakes or auxiliary wiring (eight-wire harness only).[*]Red: Use for battery charging; it connects to the starter solenoid (eight-wire harness only).[*]Light Green: Back-up lamps.[*]Brown: Taillamps and parking lamps.[*]Yellow: Driver’s side stoplamp and turn signal.[*]Dark Green: Passenger’s side stoplamp and turn signal.[*]White: Ground wire.[*]Light Blue: Auxiliary stoplamp.[/ul]

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