Global Machinery Company Sierra 1999 - Manual (Page 255)

yellow blue
4-65
Trailer Wiring Harness
Your vehicle is equipped with one of the following
wiring harnesses for towing a trailer or hauling a
slide
- in camper.
Basic Trailer Wiring Package
All regular and extended cab gasoline engine pickups
have a six
- wire trailer towing harness.
The six - wire harness is located at the rear of the vehicle
and is tied to the vehicle’s frame. The harness requires
the installation of a trailer
- wiring harness connector,
which is available through your dealer.
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.