After Adding New Lights and Rewiring Trailer the Lights Will Not Light Up

Question:

I have f 150 with 7 pin connector converted to flat 4.... hooked to trailer with new lights... nothing on trailer side. but if I touch complete lights to bumper of truck thenthey work. I have ground and cleaned all groundpoints any ideas all new wiring on trailer now too

asked by: Brian

Expert Reply:

This does sound like a ground problem since when you touch lights to the bumper they work. 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.

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