Troubleshooting the Curt Wiring Harness part # C55510 Not Functioning When Ground is Attached

Question:

Hello, I tried to install the wiring harness #C55510 on my 2007 gmc canyon and i had a couple of problems. I installed the unit and the tail lights and brake lights functioned correctly on the truck but not on cargo carrier. First i could not get the lights on cargo carrier to light up when i manually switched them on. Then i disconnected the ground from the truck and the lights turned on while the ground disconnected. Finally the lights did not work when the engine was turned over with the ground connected to the truck. I could not figure out where the fault could be and any help would be appreciated.

asked by: Jason

Expert Reply:

The first thing you will want to do is test the 4-way of the # C55510 that you installed with a circuit tester like part # PTW2993. See the video I attached to see how this is done. This will tell you if the problem is on the vehicle side or trailer side of the wiring. You will want to reinstall the harness per the installation instructions and test the 4-way with the key on.

I would make sure you have the ground circuit attached to a clean metal surface that touches the vehicle frame. It almost sounds like you have it attached to a either something with voltage or not a good ground based on the bizarre behavior you described. If you were touching the ring terminal while it was working it could have also been that you were providing the ground needed through your body.

If when you tested the 4-way for functionality the voltage was good then the problem is on the trailer or cargo carrier side of the wiring. Most likely the problem would then be ground related.

expert reply by: Jameson C