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Troubleshooting Trailer Wiring that Does not Function


I have power to trailer light wires, but neither side is working blinkers or running lights.


Expert Reply:

It sounds like you have tested the circuits of the 4-way on your tow vehicle already, but if not you will want to use a circuit tester like our part # PTW2993 and test them individually like the video I attached demonstrates.

If there is voltage there at the connector at the correct times you know the problem lies in the trailer wiring. Most likely the problem is a bad ground or corrosion. I would start by inspecting the connector looking for corrosion and cleaning if necessary.

Next, I would recommend you inspect the grounds of the tail light assemblies. If the assemblies ground through the mounting hardware you will want to make sure the assemblies are installed onto a clean metal surface.

You should also inspect the condition of the wires from the connector all the way back to the light assemblies looking for any cut or exposed wire and fix as necessary.

I attached an FAQ on trailer wiring for you to check out also.

expert reply by:
Jameson C

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