Troubleshooting Left Taillight Goes Out on Boat Trailer when I Step on Brake

Question:

I just installed lite kit and all works well except when I turn on the head lites and step on the brakes the left lite goes out but when lites are off works perfectly. any suggestions???

asked by: richard b

Expert Reply:

If you have a bad or weak ground connection this can cause the problem you are seeing. When you apply the brakes, and the headlights are on, the ground connection needs to be good because when more amperage is drawn on the system, it requires a better ground to work properly.

If you clean your ground connection points and make sure the taillights are grounded sufficiently, and the lights are still not functioning properly, you will need to check your connections and be sure you have the wires ran to the correct circuits. Use a circuit tester, # PTW2993, and test each individual wire to be sure they are wired properly. For the 4-pole harness, your wires are, white-ground, green-right turn/stop, yellow-left turn/stop, and brown-running lights. Be sure to check the vehicle and the trailer, to be sure both are wired the same. I have posted a link below to our wiring page for you to use for help with troubleshooting.

expert reply by: Robert G