Troubleshooting Ground Circuit on Trailer  

Question:

Expert Reply:

Good job in testing using a different trailer! You've effectively eliminated the tow vehicle as being the problem.

You are absolutely on the right track in suspecting a ground problem to be the cause of the issues you're having. The fact that none of the lighting functions are working would tend to rule out a loose connection or broken wire.

A trailer connector will typically ground to the trailer tongue. From the trailer connector, trace the white wire to where it attaches to the trailer frame. Make sure this connection is made tightly to metal that's not corroded. You can improve the connection by removing the screw or bolt attaching the ground connection to the trailer tongue and sanding a dime sized area around the connection down to bare metal. Reinstall the connection, but use a star washer between the ring terminal and the trailer tongue, so it'll bite into the metal. If the connection is made using a self tapping screw, go up a screw size for a tight fit. Once the connection is reinstalled, protect the connection with a coat of rust inhibiting spray paint.

Make sure all trailer lamps are grounded to the trailer frame either by a separate ground wire or by being in direct physical contact to the trailer frame. If the trailer has a tilting or swing-away tongue or a tilt bed, you can get a length of # 10-1-1 wire and two # DW05705-1 ring terminals to construct a jumper to join the movable to the stationary part of the trailer to provide a continuous ground connection. The hinge can wear over time which loads to a bad ground connection. Be sure the jumper wire is long enough to allow full movement of the hinge.

I've linked to some trailer wiring help articles that should provide some assistance.

expert reply by: Mike L

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