Troubleshooting Ground Circuit of Trailer Wiring Not Active on Trailer Wiring

Question:

I was having intermittent problems with my snowmobile trailer lights. They were working perfectly and after summer storage were not. My truck would recognize the trailer, then not and all the lights would go off, and I could see my running lights coming on and turning off as im pulling the trailer. I noticed my plug from trailer to truck was cracked and in bad shape, so I replaced it. Same issue, so I un-did it, and did it again. I have no running lights at all. I do have blinkers, brakes, and hazards. when I turn my truck lights on, I get no blinkers or hazards or brake lights. Turn them off, they all work again. Ive tested my tow vehicle with a tester and my other trailer and everything checks out like it should. Its a 4 pin connector to a 2017 F150. My trailer wiring has 2 separate brown wires for each side, one runs with yellow and one with green wire. I just separated those, and put those 2 browns together and connected to brown on the new plug. Green to green, yellow to yellow and ground to ground. Not sure what to check next? Its an aluminum trailer and all the wiring is in the aluminum tubing with LED lights.

asked by: Eric R

Expert Reply:

Sounds like a weak ground for the running light circuit that's not working currently. Since the trailer frame is aluminum make sure the ground wires of the circuits are running back to the ground circuit of the trailer connector. Typically trailer wiring grounds through the frame but on an aluminum trailer this does not work.

expert reply by: Jameson C