Trailer Wiring Harness
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
• Brown: Taillamps
• Black: Ground
• Light Green: Back-up Lamps
• Red/Black: Battery Feed
• Dark Blue: Trailer Brake*
*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 or a qualified service center.
If the back-up lamp circuit is not functional, contact your dealer.
If a remote (non-vehicle) battery is being charged, 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, turn on the headlamps (non-HID only) as a second way to boost the vehicle system and charge the battery.
See also:
Taillamps, Turn Signal, Stoplamps, and Back-Up Lamps
To replace one of these bulbs:
1. Open the tailgate. See Tailgate on page 2‑10 for more information.
2. Remove the two rear lamp assembly screws near the tailgate latch strikerpost and pull ...
Trailer Gain and Output
On vehicles with the Integrated Trailer Brake Control (ITBC) system, the trailer brake display appears in the DIC. Press the trip odometer reset stem until TRAILER GAIN and OUTPUT display.
TRAILER GA ...
New for 2010
GM has dropped the long-running 6.0-liter V-8 engine from the Sierra lineup,
leaving the powerful 6.2-liter V-8 for heavy towing needs. The rest of the
Sierra's eight-cylinder lineup benefits from ...





