Trailer Running Lights Will Not Work with 2009 GMC Acadia XLT with Tow Package

Question:

Hi we were able to get the directional signals working and the brake lights but not the running lights. Had an other person come in and try and still no running lights. I was wondering if we taped into the running lights tail light only with a 10 amp in line fuse. Would that work?

asked by: Ron L

Expert Reply:

First you are going to want to make sure that the running light circuit is working on the trailer connector on the 2009 GMC Acadia. Use a circuit tester such as # PTW2993 to test the running light circuit. If it is not working, then check the vehicle owner's manual for the fuse location for the tow package running lights to check/change it. Also check the owner's manual for any relays that might be needed for the tow package wiring.

I do not recommend tapping into the running light wire on the vehicle by itself because that adds yet another connection. The more stuff that is added the more that could go wrong.

If power is working on the vehicle side, then the issue remains on the trailer. Most likely there is a bad ground connection. Make sure that the trailer connectors are clean and free of corrosion. Then make sure the main trailer connector ground and the grounds for all of the lights are attached to clean and corrosion free bare metal surfaces.

Some things can interrupt a ground connection. A plastic license plate holder between a light and a ground location, aluminum trailer frame, tilt bed, or folding tongue all can interrupt the ground. Running jumper wires from the lights to the main trailer connector ground can help.

You can also use the circuit tester to test the wiring from the connector back to the lights to determine where the power stops. That would indicate a break in the wiring that would need to be repaired. You can also take that time to inspect and repair damage to the wires as needed.

expert reply by: Michael H