Troubleshooting Turn Signal and Brake Lights on Trailer Not Working with Headlights On

Question:

Turn signals and brake lights on trailer not working when running lights are on

asked by: Jennifer

Expert Reply:

In your case you either have an insufficient ground somewhere along your wiring or the harness is overloading the wiring connector when you turn the headlights on so some of the lights just don't get power.

Make sure your grounds are all connected to a clean, bare-metal surface and then if your trailer has an excessive amount of lights on it then you'll need to unplug some of them to avoid overloading your light circuits. If you can tell me what wiring kit is installed on your trailer I can check to see if anything else would be better for your vehicle on my end. I just need the light kit number and your vehicle year/make/model for this!

I'm also linking our wiring troubleshooting article for you to reference.

expert reply by: Jon G