[LIforrelaxin]

What do you have for a connection system for the lights.....

--- if you are running a 4 wire system with a ground wire included then somewhere on the tow vehicle there is a converter boxs that makes this all work..... they die and sometimes need to be replaced.

--- if you have a 5 wire system not sure what to tell you... have nevered used one....

--- last if like me you have a vehicle that has a 7 wire connection, and the converter is an adapter I use that puts me to the tradional 4 wire system.

Bottom line... there usually a converter to limit the number of wires.... somewhere in the system.... and they go bad.... If you can't fix the issue via ground that is probable where the problem is.

A not here on grounds..... sometime the best thing to do to check if this your problem is connect a aux. ground wire from the trailer to you vehicle chasis.......if you are having grounding issues, this well make the problem go away and then at least you know what you are dealing with......