Troubleshooting Trailer Turn Signals That Will Not Stay On When Brakes/Running Lights Are On

Updated 06/21/2022 | Published 06/18/2022

Question:

Turn signals on trailer stop working when brakes are applied or running lights are on. But work ok when no other circuit applied. I checked the ground and it’s good. Could it be a flasher relay. Please advise. Thanks.

asked by: Joel

Expert Reply:

If you've already checked your grounds and they're fine, then I also recommend checking your vehicle/trailer connectors for rust or corrosion.

You may also consider checking ALL of your wiring to ensure it's wired correctly, as well for pinches, frays or broken wires. This is another common reason why trailer lights act funny, and can be easily overlooked if not searching for it.

Finally, the last thing I recommend checking is for, is a blown fuse. You're going to need to consult the owner's manual for the location of the fuse, but you'll be looking for a fuse labeled "Trailer RT/ Trailer LT" or something to that effect.

If you're still having issues, feel free to come back and we can continue troubleshooting.

I have also included a couple of troubleshooting articles for you to check out as well.

expert reply by: Bryce D