Left Turn Signal on Trailer Will Not Blink but All Other Lights Work

Updated 09/15/2014 | Published 09/14/2014

Question:

I have an aluminium trailer and all of the lights work except for the left turn signal. What am I doing wrong? I have a four prong flat connector on the truck and the trailer.

asked by: Jeff E

Expert Reply:

This sounds like a ground issue. 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.

expert reply by: Michael H