Troubleshooting Trailer Lights and Connectors On 2002 GMC Yukon

Updated 03/18/2020 | Published 03/16/2020

Question:

have a 7way plug on a 2002 yukon and the the turn signals and brakes lights dont work when plugged into camper. Tested plug the plug not receiving power for anything but running lights.

asked by: Gladys

Expert Reply:

The first place I would check is the fuse box. The trailer turn signals and trailer running lights are all on separate circuits. The fuse box under the hood is where they are located, and they are in the front closest to the stud on the right side. They're labeled TRL R TRN and TRL L TRN. You can find the diagrams for the fuse boxes on page 6-70 of your owners manual.

If the fuses are blown, they will need to be replaced and you can recheck the functions at the connector on the back of your Yukon. The 7 Way Trailer Connector Vehicle Tester # C73NR is an easy way to test the functions.

If the fuses are blown and you replace them and they blow again there is most likely a short in the wiring. I recommend visually inspecting the wiring at the connector, and checking for frayed wires or corrosion. You can also take the 7 way apart and check the connection inside and make sure none of them are crossing over to another terminal.

If you are still experiencing issues with your trailer lights let me know so I can look further into it for you.

expert reply by: Robert C