It's a constant battle keeping trailer light working. I need to use my 10' trailer so I hooked to it and checked the lights, they wouldn't light up like they should so I knew there was a ground problem. I just used it a couple weeks ago and everything was fine. Replaced the bolt & terminal where the harness from the truck is grounded to the tongue & they still won't work. It is a tilt trailer so I attached a jumper from the main frame to the tongue and they worked so I made a permanent ground near the pivot point. It should have a ground wire all the way to the lights but it's a factory made trailer so of course it's made as cheap as possible. Needs new lights anyway so I may just do that.