When installing a trailer brake module or trailer connector on a 2003-06 Chevrolet Express or GMC Savana with RPO Z82 and/or UY7, it is necessary to know the location of the harness and what each wire is used for.
The four-wire trailer brake controller harness is located on the driver's side, under the instrument panel, taped to the pass-through main harness, between the park brake pedal and the vehicle brake pedal.
The seven-wire harness assembly is taped together and located in a frame pocket at the driver side rear left corner of the frame.
TIP:Â Both harnesses come without connectors.
The following tables include the color of each blunt-cut wire and its purpose.
- Thanks to Ron Erman
Four-Wire Harness | |
Black | Ground |
Red/White Stripe | Fused Battery |
Dark Blue | Trailer Brake Feed |
Light Blue | Fused Stop lamp/CHMSL |
Seven-Wire Harness | |
Light Green | Back-up lamps |
Brown | Parking lamps |
Yellow | Left stoplamp and turn signal |
Dark Green | Right stop lamp and turn signal |
Dark Blue | Electric trailer brakes |
Orange | Trailer accessory |
White (heavy gage) | Ground wire |
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