K 3500 Truck 4WD V8-6.6L DSL Turbo VIN 1 (2001)
Trailer Connector: Service and Repair
This article was created from GM service bulletin #02-05-22-004C - (Apr 5, 2005) - Trailer Brakes Applied When Headlights/Park Lamps Are
On, Brake Controller Illumination (Modify Brake Controller Wiring Harness)
Condition
Some customers may comment that when the headlamps or park lamps are on, the brakes on the trailer are always applied, or that the back lighting for
the trailer brake controller only illuminates when the brakes are applied.
Cause
The cause of this condition may be due to wiring changes within the vehicle electrical system for the 2003 model year.
Correction
Inspect the brake controller wiring harness jumper that is plugged into the vehicle relay block-body. The relay block-body is located under the left side
of the instrument panel near the left kick panel, behind a plastic cover.
The 1999 though early 2003 wiring harness jumper that plugs into the relay block will have a reddish/brown 6-way connector and a tag with the last
four digits of the wiring harness part number. Second design 2003-05 may have a white plastic connector with part number 5418 as well.
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The 1999 jumper is/was P/N 12171982 with a pink/purple tag identifier of 1982. This number has been superseded to 15366255, with a
pink/purple tag identifier of 6255.
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The 2000 jumper harness is P/N 15366255. The pink/purple tag identifier is 6255.
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The 2001-2002 jumper is P/N 15086884. The orange tag identifier is 6884.
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The 2003-05 jumper is P/N 15085418. The orange tag identifier is 5418.
When transferring the brake controller with the wiring jumper attached from a 2001-2002 vehicle to a 2003-05 vehicle, a change to the jumper harness
connector must be performed.
