Trailer Lights Not Working After Installing New Lights and Wiring

Question:

I have a 2002 Ford Ranger just put new wire harness and lights on my trailer but now neither lights work when I turn on the turn signal in the truck.I did check all the fuses in the cab of the truck,but the fuses under the hood you cant tell if they are bad.Could it be a bad wire harness that comes from the truck?.

asked by: LEE M

Expert Reply:

This sounds like a ground issue. Ground problems normally show up when there is more draw on a system such as when you have the running lights on and then use another function like a turn signal or brake light but can show up any time.

To determine if the issue is in fact a ground problem and not the vehicle side trailer connector you can test the truck side using a circuit tester such as # PTW2993. I have linked a help article on testing vehicle side connectors for you.

Make sure that the vehicle side and trailer side connectors are clean and free of corrosion inside and out. The main connector grounds should be attached to clean and corrosion free bare metal surfaces.

The light grounds should also be attached to clean and corrosion free bare metal surfaces. If there is anything between a light ground and the metal trailer frame or if the trailer has an aluminum frame, tilt bed, or folding tongue, any of these things can interrupt the ground. Running jumper wires from the light grounds to the main trailer connector ground can help.

expert reply by: Michael H