Troubleshooting Lack of Trailer Tail Light Function on 2016 Ram 5500

Published 11/20/2018

Question:

When I connect my trailer, I have no lights. Had a local Diesel shop check both the truck and the trailer. They claim the vehicle computer is shutting down the trailer lighting. Is this possible?...and Why?

asked by: Junior

Expert Reply:

If it is just the lack of taillights and all the other functions work like brake lights and turn signals, then Fuse F-29 under the hood is a notorious offender. You can check this using a circuit tester like # PTW2993. The left and right turn and brake light functions are found at the 3 and 9 o'clock pin positions on your 7-way. The running/taillights are found on 11 o'clock pin. I've attached a photo to assist.

I haven't heard of any vehicle computer shutting down the trailer lighting, but most dealers don't check this fuse prior to diagnosing another issue. I'd start there.

If that doesn't solve the issue, we can continue to troubleshoot.

expert reply by: Jason S