2008 GMC Envoy Owner's Manual - Page 294

Trailer Wiring Harness The seven-wire harness contains the following trailer circuits: Yellow: Left Stop/Turn Signal Dark Green: Right Stop/Turn Signal Brown: Running Lamps White: Ground Light Green: Back-up Lamps Red: Battery Feed Dark Blue: Electric Brakes If you need to tow a light-duty trailer with a standard four-way round pin connector, an adapter connector is available from your dealer. Your vehicle may be equipped with the seven-wire trailer towing harness. This harness has a seven-pin universal heavy-duty trailer connector (if equipped with the trailering package) that is attached to a bracket on the hitch platform. If your vehicle is not equipped with the heavy-duty trailer connector, you may purchase one from your dealer. If you are charging a remote (non-vehicle) battery, turn on the headlamps to boost the vehicle system voltage and properly charge the battery. Your vehicle may also be equipped with wiring for an electric trailer brake controller. These wires are located inside the vehicle on the driver's side under the instrument panel. These wires should be connected to an electric trailer brake controller by your dealer or a qualified service center. 4-56