| Subject: | Installation of an Aftermarket Trailer Brake Module |
| Models: | 2004-2007 Buick Rainier |
| 2002-2007 Chevrolet Trailblazer and Trailblazer EXT |
| 2002-2007 GMC Envoy, Envoy XL and Envoy XUV |
| 2002-2004 Oldsmobile Bravada |
This PI was superseded to update model years. Please discard PIT3204C.
The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.
Condition/Concern:
To aid in the installation of a trailer brake module, 2002-2007 mid-sized utilities are equipped with a blunt cut jumper harness.
Recommendation/Instructions:
This vehicle may be equipped with the seven-wire trailer towing harness. This harness has a seven-pin universal heavy-duty trailer connector that is attached to a bracket on the hitch platform.
The seven-wire harness contains the following trailer circuits:
| • | Yellow: Left Stop/Turn Signal |
| • | Dark Green: Right Stop/Turn Signal |
| • | Light Green: Back-up Lamps |
| • | Dark Blue: Electric Brakes |
| • | Red: Battery Feed (The chassis wiring ring terminal must be fastened to a stud on the underhood electrical center before the trailer feed will become active.) |
The electric trailer brake controller jumper harness is located inside the vehicle, driver's side, above the floor close out panel. Lower the close out panel and follow SP205 toward the drivers pass through door harness. Attached to this body harness,
there will be a label and 4 blunt cut wires.
Four-Wire Harness (Trailer Brake Controller)
| • | Orange: Fused Battery Positive Voltage |
| • | Dark Blue: Trailer Auxiliary Supply Voltage |
| • | Light Blue: Fused Stop lamp/CHMSL |
2002-2006 Schematics for these circuits can be found in eSI under (Body > Lighting System > Schematic and Routing Diagrams > Exterior Lights Schematics > Trailer Wiring).
2007 Schematics for these circuits can be found in eSI under (Body Systems > Lighting > Schematic and Routing Diagrams > Exterior Lights Schematics > Trailer Wiring UY7
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.
