Troubleshooting Trailer LED Turn/Stop Lights Not Working with Headlights on

Updated 03/31/2020 | Published 03/30/2020

Question:

Dont understand it!!! I have hooded up my new LED trailer lights and they are having issues. The break lights work, the turn signals work, but when I turn on the driving lights they all stop working. Yet the yellow driving lights on the side of the trailer work. I have a test set of LED trailer lights for towing cars and they work fine when connected to the truck. What gives?

asked by: Jim E

Expert Reply:

There are 2 possible reasons why your LED lights aren't working when you turn your headlights on; the first (and more likely) is that you have a bad ground or grounds, and the second is that you have too many LED lights on your trailer.

Start off by checking all of the grounds connected to the lighting on your trailer. Make sure they are all securely connected to a clean, bare-metal surface. Also check the pin for the ground on your trailer connector while you're at it. I have attached a photo showing the pin locations for a 7-Way for you to reference. On the 4-Way connector your trailer ground will be the 1 pin that looks different.

If all of your grounds are good then the next step would be to slowly disconnect different LED lights until everything starts working. Then you can note what the max amount of lights you are able to have installed and you can adjust everything accordingly.

Attached is a link to our selection of helpful articles on wiring that you can also check out.

expert reply by: Jon G