Turn Signals Not Working After LED Light Install

Question:

I mounted new led lights that do running lights, brake and turn and reverse. Each light has a red wire a green wire and a black wire. I attached all wires to my factory harness and all functions work except left and right turn. Heres the kicker. With four ways turned on they work. With just left or right turn on they only work if i touch with grounded test light. Im puzzled.

asked by: Stuart

Expert Reply:

If the LED taillight you are using has four functions and only three wires, that means that the light grounds though the mounting hardware. Before I begin to troubleshoot connection issues, I would first sand the surface down used to mount the light and make sure that the mounting hardware is securely attached. The good majority of erratic lighting problems are associated with a ground issue.

The next step I would take would be to check to ensure each wire is attached to the proper function. There is not always a standard wire color to function on trailers therefore it is best to test for function on the trailer using a circuit tester like part # PTW2993. The light should have listed which wire colors represent which function.

Another common problem with installing LED lights on a trailer is that the new LED turn signal bulbs draw much less power than the old incandescent turn signal bulbs therefore an error occurs. This error is usually attributed to an action know as hyper-flash but it could also cause the bulbs not to work entirely. In order to fix this you would need to install a load resistor like part # DI34ZR on each of the trailer's turn signal circuits.

Let me know once you have performed the above steps and if the issue still persists, I would be glad to provide further troubleshooting advice.

expert reply by: Conner L