Trailer Electric Brake Wiring Troubleshooting on 2015 GMC Sierra 3500
Updated 03/06/2018 | Published 03/05/2018
Question:
Where is the trailer brake relay located on a 2015 gmc sierra 3500
asked by: Katie P
Expert Reply:
In the Engine compartment on the driver's side, there is a fuse block. In the #1 location there is a micro J-case fuse for the Trailer Brake. There is not a relay for this on your 2015 GMC Sierra 3500. Your owners manual does have a relay on the driver's side of the vehicle, next to the under hood electrical container that is used to supply power to additional equipment. This isn't specified as being part of the trailer brake system. This is stated in the online owners manual on page 9-88.
You can use a circuit tester like # PTW2993 to test wiring functions and pin locations.
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