| Subject: | Harness Location For Trailer Brake Installation RPO Z82 and/or UY7 |
| Models: | 2003-2007 Chevrolet Express |
This PI has been revised to add the 2007 model year. Please discard PIT3514B.
The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.
Condition/Concern:
When installing a trailer brake, it is necessary to know the location of the harness and what each wire is used for.
Recommendation/Instructions:
The trailer brake 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 vehicles 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. Both harnesses come without connectors. Below is a description or purpose for each blunt cut wire. Please use this as a guide to aid with the installation of a trailer brake module or trailer connector
at the rear of the vehicle.
Four-Wire Harness (Trailer Brake Controller)
| • | Red/White Stripe: Fused Battery |
| • | Dark Blue: Trailer Brake Feed |
| • | Light Blue: Fused Stop lamp/CHMSL |
Seven-Wire Harness (Trailer Light/Brake Wires)
| • | Light Green: Back-up lamps |
| • | Yellow: Left Stoplamp and turn signal |
| • | Dark Green: Right stop lamp and turn signal |
| • | Dark Blue: Use for electric trailer brakesDark Blue: Use for electric trailer brakes |
| • | Red/Black: Trailer accessory (The chassis wiring ring terminal must be fastened to a stud on the underhood electrical center before the trailer feed will become active. This is a single Red/Black wire wrapped in black electrical tape next to the
UBEC.) |
| • | White (heavy gage): Ground wire |
Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.
