Trailer Lights Do Not Light Up When Connected to 2007 Subaru Outback with Working Wiring Harness

Question:

Hi. My Subaru has a tow package which when tested with a little flat 3 pronged tester works fine. All lights come on. I purchased a new light package for the trailer, hooked it up and then when I connected it… nothing! I have cleaned the ground on the trailer, and all wires are new. I cannot figure out whats wrong.

asked by: Rich

Expert Reply:

Since the new wiring harness on your 2007 Subaru Outback has power the issue must be on the trailer side. It does sound like a ground issue. There are numerous grounds on a trailer so there are a few places to check.

Make sure that the vehicle side and trailer side connectors are clean and free of corrosion inside and out. The main connector grounds should be attached to clean and corrosion free bare metal surfaces.

The light grounds should also be attached to clean and corrosion free bare metal surfaces. If there is anything between a light ground and the metal trailer frame or if the trailer has an aluminum frame, tilt bed, or folding tongue, any of these things can interrupt the ground. Running jumper wires from the light grounds to the main trailer connector ground can help.

expert reply by: Michael H