Finding and Repairing Poor Ground Connection on Trailer

Updated 08/30/2014 | Published 08/29/2014

Question:

If I turn on running lights brake and turn stop working and cant get any running lights at all

asked by: Derrick J

Expert Reply:

What you're describing is the classic symptom of a poor ground connection somewhere in the trailer wiring on the vehicle or on the trailer. Everything works fine until you draw maximum amperage through the system by turning on the running lights. Check the ground connection on the vehicle where the trailer connector attaches to the vehicle frame or chassis. Make sure this connection is tight and not corroded.

Trace the white wire from the trailer connector back onto the trailer tongue, and find the point where it grounds to the trailer frame, usually on the trailer tongue somewhere. Make sure this connection is also tight and not rusted. Your trailer lamps will pick up their ground connection in one of two ways, either by their mounting hardware being in direct contact with the trailer frame or by their own ground wires that attach to the frame. Makes sure these connections are all sound. If the trailer has a tilting bed or a folding or tilting tongue, the pivot point can become a little loose over the years, and not provide a continuous ground connection. A simple fix is to get a short length of wire, place a ring terminal on either end, and use the wire as a jumper to join both sections of the trailer to keep the ground connection continuous.

expert reply by: Mike L