Troubleshooting Trailer Running Lights Blowing Vehicle Fuse when Head Lights are Turned On

Question:

Ok I solved the problem with the right side ,now my issue is that when I turn on my lights the running lights on the trailer blows the fuse sounds like a ground problem

asked by: DAVID F

Helpful Expert Reply:

Since turning on your headlights blows the fuse for your running lights on your trailer, the issue likely isn't a ground but rather a short. It sounds like the lesser power draw doesn't blow the fuse, yet when that draw changes with the headlights, the surge causes the issue. The issue has to be that the circuit shorts to cause that fuse issue. I recommend tracing that wire and checking for any fraying, kinks, or missing insulation where that wire may short to the frame or another wire.

If it is a ground issue, then it would likely be on the vehicle side and not the trailer side, but you can test that using a multimeter like # PT89ZR on your trailer connector when the trailer isn't connected. That will give you a reading on your running light circuit that shouldn't fluctuate much when your turn on your headlights.

expert reply by: Jason S