Troubleshooting Trailer Wiring That Stops Lighting Up When Brakes are Applied

Question:

My husband hauls RVs. Brand new campers, trailers, etc. Recently every time he hits the brake, every trailer he pulls almost goes dark. No lights. As soon as the brake is off, all the lights are fine. Like I said, these are brand new, so no corrosion, no old wiring. The truck he pulls with is a 2006 Chevy Silverado Duramax 2500. Any advice would be greatly appreciated!

asked by: Jill P

Helpful Expert Reply:

Sounds like a weak ground. The brake light circuit of trailer wiring will pull the most amperage as the brake lights are the brighter illumination circuit on the taillights. Typically when this circuit causes the lights of the trailer to turn off the issue is a weak ground not being able to keep up with the amperage draw requirements. If he isn't popping fuses on the tow vehicle then that also would indicate a weak ground. Best option is to go over the trailer wiring connector on the truck to see if you can find anything that would cause an insufficient ground like corrosion and fix as needed.

I also attached a link to a page on trailer wiring troubleshooting as well.

expert reply by: Jameson C