Trailer Running Lights Go Out After Short Time Towing Trailer with a 2009 Toyota Highlander

Question:

Running lights work for about one-half hour then go out. The trun signals and stop lights are still working. I disconnect the plug and re and the lights come back on but go out again in ten minutes. Any ideals?

asked by: Paul C

Expert Reply:

This sounds like a possible ground problem or dirt/corrosion in the trailer side or vehicle side connectors. Ground issues can be fixed by checking the trailer connector and trailer light grounds and making sure they are attached to clean and corrosion free bare metal surfaces.

On the trailer connector pins you can use a sharp tool or wire brush small enough to fit and clean out the dirt and corrosion if present.

You can also check to see if the running light power draw is close to or exceeding the capacity of the trailer wiring harness on the vehicle side or the vehicle itself. If the trailer has a large amount of running lights then you can try reducing the number of lights as a test to see if that fixes the problem. If it does but you want to keep all the lights I recommend switching everything over to LEDs which have a much lower power draw.

expert reply by: Michael H