Troubleshooting Installing New LED Lights on Trailer and Only All Work With Headlights On

Question:

I rewired my trailer and put new led taillights on it. I also used new wire and used a 7 pin plug with a jbox. The problem I am having is when I turn on the truck I have to turn my lights on to get power to the lights. Also o ly the brake lights come on and nothing else. I have used a circuit tester and all test good in the jbox. I have lights grounded in the box and out of the box to the trailer. What could be causing this issue?

asked by: Jamie H

Expert Reply:

Sounds like you have the stoplight and the running light circuits wired backwards on your new trailer lights. I'd try switching the circuits you have ran on the light assemblies to see if that helps get the lights to work again.

expert reply by: Jameson C