Trailer Turn Signal Does Not Work when Running Light Wire is Connected

Question:

So, all the running lights are working and the drivers side turn signal and break light are also working. On the passenger side, the running light works, but no turn signal. If I disconnect the wire for the running light brown the turn signal works. Once the running light is reconnected the turn signal stops flashing again. I have verified a good bond to ground and correct voltage at the trailer light for both brown and green wires... I have visually inspected for a short in either the brown or green and have found none. Please let me know what Im missing. Thanks

asked by: Chris H

Expert Reply:

This does sound like a ground issue or could possibly be a short internal to the light. Ground problems normally show up when there is more draw on a system such as when you have the running lights on and then use another function like a turn signal or brake light.

Make sure that the vehicle side and trailer side connectors are clean and free of corrosion inside and out. The main connector grounds should be attached to clean and corrosion free bare metal surfaces.

The light grounds should also be attached to clean and corrosion free bare metal surfaces. If there is anything between a light ground and the metal trailer frame or if the trailer has an aluminum frame, tilt bed, or folding tongue, any of these things can interrupt the ground. Running jumper wires from the light grounds to the main trailer connector ground can help.

If that doesn't take care of the issue then there could be something wrong inside that light itself and not externally where you could easily find and fix it.

expert reply by: Michael H