GMC 2001 Sierra - Manual (Page 300)

4-78
The six - wire harness contains the following
trailer circuits:
D Yellow: Left Stop/Turn Signal
D Dark Green: Right Stop/Turn Signal
D Brown: Taillamps
D White: Ground
D Light Green: Back
- up Lamps
D Light Blue: Center High - Mounted
Stoplamp (CHMSL)
If you need to upgrade your vehicle to heavy - duty
trailering, a brake controller harness and an underbody
harness with a seven
- pin universal heavy - duty trailer
connector are available from your dealer.
Heavy - Duty Trailer Wiring Package (If Equipped)
Your pickup may be equipped with the eight - wire trailer
towing harness. This harness with a seven - pin universal
heavy - duty trailer connector is attached to a bracket on
the platform hitch.*
* The Center High - Mounted Stoplamp (CHMSL) wire
is tied next to the trailer wiring harness for use with a
trailer, slide
- in camper or cap.