Trailer Turn Signals Blink Opposite of What they are Supposed To

Published 07/23/2015

Question:

Need to know my problem. Hook up trailer lights four post hook up. Tail lights work . Problem is the turning signals . turn my left signal on an right one blinks and vise versa.

asked by: Mike

Expert Reply:

It sounds like there are either some crossed wires or a bad ground (weird things can happen when there is a ground problem).

On a trailer side 4-Way the covered pin is the ground. Next to it is the running lights. The third pin is left turn signal and brake lights, and the last pin is right turn signal and brake lights. It is possible that either on the trailer or vehicle the last 2 functions are swapped.

Also 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.

I have included some links that should also help.

expert reply by: Michael H