Potential Grounding Issue When Installing Peterson License Plate Light # PM436B

Question:

I spliced the single wire from the PM436B into the brown wire on the TL21RK, and it wont work. The bulb seems fine. Trailer lights work fine. Could it be that the paint on the trailer frame a light spray paint coat is preventing grounding? I have also spliced more wire onto the PM436B for length, and the connection is fine. What else could be wrong? If I cant get this to work, I will return the PM436B and order the LPL55CB, which has its own ground wire. Thanks.

asked by: Kurt S

Helpful Expert Reply:

Thank you for your recent purchases from etrailer.

A bad or insufficient ground is among the most common causes for issues with trailer lighting. The
Peterson License Plate Light # PM436B that you have does use its steel mounting surface to make the ground connection required for proper operation. Connecting the lead wire to the brown wire for the running light circuit as you did is correct. Please see the linked video for reference.

You can sand off paint from the trailer frame where the light mounts. This bare metal-to-metal is essential. It may also be necessary to sand some of the paint on the rear surface of the light's bracket to provide a sufficient ground. You can use dielectric grease like # LT37534 to protect those bare metal surfaces.

Another option is to run a 10- or 12-gauge ground jumper wire from the back surface of the light bracket to another bare metal spot on the trailer frame. If sanding off the paint does not correct the issue then the jumper wire should take care of it.

expert reply by: Adam R