Power Getting to Trailer Tail Light with a Good Bulb but the Bulb Does Not Light

Updated 03/06/2013 | Published 03/03/2013

Question:

Hello, I have an old boat Im repairing and recently replaced the trailer lighting kit with a peterson v540 kit. my truck is a 2001 gmc sierra 1500. I have a propper ground that is shared to both the left and right side wiring, and i have replaced the fuses used for trailer lighting. the bulb is good and power goes to it but it will not light? any idea?

asked by: Robert

Expert Reply:

If power is getting all the way to the light and the bulb is good but will not come on that indicates to me that the circuit is not being completed. This would mean the ground is the problem. You can test this pretty easily by attaching the ground from the affected light directly to a negative battery terminal. The light should come on.

The lights should be grounded independently and as close to where they are mounted. There should be no corrosion, paint or dirt on the ground location. Sometimes if a plastic license plate holder is attached between the ground and frame that will cause this problem.

If you have an aluminum frame, tilt trailer, or folding tongue you will need to run jumper ground wires from the lights to the main trailer connector ground location.

expert reply by: Michael H