Trailer wiring harness instructions

B

bczoom

Member
This applies to GM trucks. Not sure about others.



Starting with the all new 2007 Full Size Utilities there is no longer an electric trailer brake controller pigtail harness. The trailer brake controller wiring is now part of the I/P wiring harness and the blunt cut wires are located under the left IP, behind the DLC. There are four blunt cut wires in this harness which are:

Wire Color
Circuit#
Description
SI Document ID #

Red/Black
242
12 Volt power supply (30A Stud 2)
1762159

Dark Blue
47
Trailer brake output voltage
1762159

White
22
Ground
1762159

Light Blue/White
6311
Stop light input
1762159


Note: The Red/Black circuit 242 must be connected to Stud 2 30 Amp of the UBEC. The wire is located between the left fender and UBEC. Do not confuse this circuit with 742 (Doc Id 1762158) which is also Red/Black taped to the harness under the master cylinder, which is the 12 volt supply to the 7-way trailer connector and connects to Stud 1 40 Amp.
 
Watch out on that Stop Light output. It is a very thin wire with a very thin very light blue line. Ask me how I know and I'll point you to another thread.:whistle:
 
Thanks for this guide. I have gained some insights to apply to my business at Fairfax. It is through these communities that we get to learn a lot.
 
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