Troubleshooting Trailer Taillight Malfunction Connected to a 2006 Volkswagen GTI

Question:

Thought I had the right connections but when headlights running lites off brake and turn signals on trailer work okay..when headlights on trailer lights come on but no turn and brakes lights work..frustrating

asked by: Gary K

Expert Reply:

It sounds like you might have a ground problem on the trailer side of the wiring. Nearly every time there is bizarre behavior on the tail lights of a trailer its because of a faulty ground. I would inspect the wiring for exposed wire/corrosion and fix as necessary. I would start at the trailer connector looking for corrosion and then work your way back to the taillight assemblies. A lot of light assemblies ground through the mounting hardware, so you may need to check where that your assembly is attached to clean metal surface.

Another issue you might have is that your tail lights are only single intensity and can only do one function at a time.

You could also have your trailer wired up incorrectly. Check out the FAQ article I attached on wiring to see how your trailer should be wired up.

expert reply by: Jameson C