LED Trailer Tail Lights Work with Flashers and Running Lights But Left Turn and Brake Do Not Work

Updated 03/10/2014 | Published 03/08/2014

Question:

I have Wesbar LED trailer lights on my boat trailer . Recently I began having problems with the left rear light . I have running lights and 4 way emergency lights , however the left side directional and the left side brake light doesnt work . I have cleaned the plug , checked the wiring and do not see any problems . Is it possible that the diode is the problem , and if it is , is it possible to change out just this specific diode ? I patiently await your response !

asked by: Dennis

Expert Reply:

If the running lights and flashers are working on all the lights then it is not likely a problem with one diode. To determine what the problem might be you can do a little testing. Using a separate 12 volt battery you can connect the light directly to the battery. If it lights up like it is supposed to then the issue is somewhere other than the light.

If the light does not work properly then you will need to replace it since the diode circuitry is not available by itself.

I suspect a loose or broken connection or a bad ground somewhere that is causing the problem. Make sure the light grounds and the main trailer connector ground are all connected to clean and corrosion free bare metal surfaces. Inspect the wiring for any frayed wires or breaks and fix as needed.

If you have added a license plate bracket between a light ground and the trailer frame, have an aluminum frame, tilt be, or folding tongue then any of those things can interrupt a ground connection. Running jumper grounds from the lights to the main trailer connector ground can help.

If you continue to have problems there could be a problem on the vehicle side wiring. Make sure its connector is clean and free of corrosion. I have included a link to a help article that explains how you can test the vehicle side wiring.

expert reply by: Michael H