What Could Cause My Left Turn Signal and Left Brake Light Not to Work

Updated 09/07/2021 | Published 09/02/2021

Question:

I have checked the connection at the tow vehicle with another camper and the break light and turn signals work but when I hook up to my new to us camper the left side does not work. I get a message on my tow vehicle that left turn signal module not working what is that i put a new 7-way plug and wire on and still same results. I took my test light and pulled the light assembly down to test and I am not getting any power to the brake or signal side of the light fixture. I am at loss for words. We just bought the camper 3 weeks ago and the previous owner had just gotten it inspected the day before we picked it up. The turn signal was not working then but I thought it was a bad bulb. Put new one in and nothing.

asked by: Emmett

Expert Reply:

The brake lights and turn signals for each side are on one circuit, normally the left side is a yellow wire. The first thing I would suggest to check is the fuse on your tow vehicle.

If that checks out ok, you should check the trailer connector at the end of your tow vehicle. You can use a tester like the Circuit Tester Kit # PTW2993. If you determine the issue is there you will need to clean the connector. If that doesn't that doesn't fix it the problem is in your vehicle.

If the connecter tests out okay, then the problem is with your camper. You'll want to check the trailer connector on your camper, as well as all the wiring on the left side of the camper. You will want to make sure all the wires are in good shape, not damaged or pinched. You will also want to check the ground wires on each light and make sure they are all connected to a clean, smooth surface.

If you find any wires that are damaged, you will need to replace them and then you can retest the lights.

I have attached a diagram to help illustrate the wiring on a trailer.

expert reply by: Thomas M