Troubleshooting Trailer Lights That Are Dim When Trailer Is Not Hitch To Hitch Ball On Tow Vehicle

Published 09/21/2021

Question:

i hook my cable to my truck but i dont put the trailor on the ball i hit the brakes and all lights come on but are dim is this because the rv isnt hooked to the truck through the ball??

asked by: Gerald

Expert Reply:

The lights on your trailer should work the perfectly even though the trailer is not hitched to your hitch ball. The trailer is grounded through the trailer connector and not the hitch ball so being hooked up makes no difference.

If the trailer lights work correctly when you hitch the trailer to the hitch ball then the issue is the main ground on the trailer tongue is not good due to either corrosion or being loose causing the lights to be dim.

I would check all of the trailer grounds and if the connector on your truck is an aftermarket harness then check that the ground for it is also securely connected.

I included a link to a helpful article on trailer wiring for you to take a look at.

expert reply by: Samuel C