GMC 2001 Envoy - Manual (Page 274)

4-58
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” in the Index. 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.
D Dark Blue: Use for electric trailer brakes or auxiliary
wiring (eight - wire harness only).
D Red: Use for battery charging; it connects to the
starter solenoid (eight - wire harness only).
D Light Green: Back - up lamps.
D Brown: Taillamps and parking lamps.
D Yellow: Left stoplamp and turn signal.
D Dark Green: Right stoplamp and turn signal.
D White: Ground wire.
D Light Blue: Auxiliary stoplamp.
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.