Trailer Wiring

I have a 94 Ram Van and I wired a 4 plug flat connector to the existing wires at the rear of the vehicle. The guys at any U-haul can tell you which one is correct for a standard hookup. I used left stop, right stop, running lights and ground. I hard-wired it in using solder and shrink tubing and it's been good for over 10 years. If you want to take a drive up to Grass Valley I can troubleshoot it for you but it sounds like something is bouncing around and shorting to ground.