Troubleshooting Trailer Lights with Only the Right Turn Signal Working

Updated 04/22/2010 | Published 04/21/2010

Question:

I have a 2000 Silverado. I parked and unhooked my on a Sat. all lights on trailer working. Hooked the traler back up on Wed. , plugged the adapter into my towing package truch plug and no running lights, sidelights or brake lights. Only my trailer right turn signal would work. Both tail lights would flash whne I turned my emergency flasher on for a while. All of my lights on my truck works fine. what do you think is my probelm?

asked by: Harvey M

Expert Reply:

This sounds like either a ground problem or a loose or broken wire causing your problem. First, you will need to check for a proper ground at the connector and at each light. The taillights are grounded through the mounting bolts. I have included a video that explains how to test for a proper ground. Basically, you will test wire the brake light wire that is supposed to be hot when you step on the brakes. If you cannot get a signal at the taillights, you might have a bad ground and you will need to try grounding in a different location.

If you cannot find a ground problem, you can move on to wiring. First, test the vehicle side connector with the trailer detached. You will need to check the functions to make sure they are working properly. Using a circuit tester, like # PTW2993, test the connector for left turn and brake, running lights, and right turn and brake. If everything is working properly, move on to the trailer.

You will need to check the wires that carry the signal to the lights from the trailer connector, all the way back to the trailer lights. First, you will have to find the correct wires. Using a circuit tester, find the wire that only carries a signal when you step on the brakes. Once you find the wire, test it at various locations throughout its length to find if it is broken at any point. At the same time you can check to see if any connections on that wire are loose. Do the same for the other wires and functions.

expert reply by: Michael H