Why Would Trailer Wiring Work When Headlights are On

Question:

Why do the trailer lights work with the headlights on and dont work with the headlights off?

asked by: Gene

Expert Reply:

The trailer running light circuit is designed to activate when the vehicle has it's head lights and/or running lights on. So what you are seeing very likely normal. BUT if the stoplights and blinkers only work when the headlights are on then that is definitely a problem. If that is the case I would assume it has a ground issue on the trailer wiring. I would recommend then going over the grounds of the light assemblies and the main ground of the trailer wiring that attaches to the frame. Or it could be that the ground pins of the trailer wiring connects are dirty and just need to be cleaned off.

expert reply by: Jameson C