Maintenance When Trailer Towing; Trailer Wiring Harness - GMC 1999 Envoy Owner's Manual

Maintenance When Trailer Towing

Your vehicle will need service more often when you're
pulling a trailer. See the Maintenance Schedule for more
on this. Things that are especially important in trailer
operation are automatic transmission fluid (don't
overfill), engine oil, axle lubricant, belt, cooling system
and brake system. Each of these is covered in this
manual, and the Index will help you find them quickly.
If you're trailering, it's a good idea to review these
sections before you start your trip.
Check periodically to see that all hitch nuts and bolts
are tight.

Trailer Wiring Harness

-
The heavy duty trailer wiring is an eight
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
-
an in line fuse located by the junction block. See "Fuses
and Circuit Breakers" in the Index. The harness does not
have a 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.
4-54
-
wire harness
-
amp feed wire with
D
Red: Use for battery charging; it connects to the
starter solenoid.
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 (Heavy Gauge): Ground wire.
D
White (Light Gauge): 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.
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