Trailer Left Blinker Lights Up when the Right Blinker is Turned On

Question:

When the right truck blinker is on, the left blinker activates.

asked by: Lori F

Expert Reply:

There could be a short or a ground problem that is causing the left blinker to turn on instead of the right. To determine where the issue is you can disconnect the trailer and use a circuit tester such as # PTW2993 to test the vehicle side connector.

If you have the same problem at the trailer connector, then the issue is on the vehicle side. But if the vehicle side is correct then the issue is on the trailer. In either case make sure that the vehicle and trailer side connectors are clean and free of corrosion inside and out.

You can inspect the trailer wiring for breaks or pinches but it doesn't seem like that is the issue. 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.

expert reply by: Michael H