Troubleshooting Boat Trailer Right Tail Light and Running Lights Not Working  

Question:

Helpful Expert Reply:

When trailer lights aren't working, the best place to start is to determine if the issue is on the tow vehicle or on the trailer. You've swapped a couple of things out, but there are still a number of places there could be wiring issues.

A circuit tester, like the LCD Digital Circuit Tester # PTW2992, is a great tool to use to test the vehicle-side wiring and the trailer-side wiring. Start by testing for all of the functions at the vehicle-side plug. As long as all of the functions (stop, turn, and taillights) work at the vehicle plug, then we can be sure that the issue is on the trailer's wiring. If any of those functions are not working on your vehicle, then the issue is somewhere between the plug and where the trailer wiring connects to your vehicle. Check for any damaged wires that could be causing a short.

If the testing indicates that the issue is on the trailer-side, start at the trailer plug and check for any damage or corrosion at the connector. From there, follow the wiring back to the lights to make sure there aren't any pinched or damaged wires on the trailer that could be causing your right-side light and running lights not to work. If the wires are ran through the boat trailer frame, the inside of the frame may be starting to rust and rubbing through the wiring insulation and possibly causing the wires to short. You also mentioned that you've replaced the ground connectors, but make sure the grounds are attached to a clean, bare metal spot on your trailer to give them the strongest ground connection possible.

If these troubleshooting steps don't offer a solution, please let me know and we'll move forward from there.

expert reply by: Victoria B

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