Troubleshooting 2004 Ram 2500 - Left Turn And Brake Lights Don't Work With Trailer Hooked Up.

Updated 04/01/2024 | Published 03/27/2024

Question:

I have a 2004 Dodge Ram 2500, all the lights work but the left turn/brake light doesnt work when plugged into the 4-pin or 7-pin. Fuses look good, same with the wiring. Any ideas?

asked by: Cole T

Expert Reply:

Hello Cole. The issue you are describing sounds a lot like an issue with the trailers wiring. Most likely either a bad ground or a short circuit. A bad ground can cause all sorts of issues, and it would certainly explain why problems only arise when the trailer is hooked up.

The first thing I suggest doing is checking your ground on the trailer and make sure it is connected to good clean metal free of rust or corrosion. Taking some sandpaper to the frame and using a new ring terminal should resolve the issue. If it does not, I suggest going in with a Circuit Tester like part # PTW2992. You can test the wires on the trailer end, specifically the left turn and brake wires and pinpoint the cause of the issue. You will be looking for any damaged, cracked or frayed wires that could be causing a short. I also suggest testing the wires behind the 7-pin and 4-pin on your vehicle to make sure they are showing proper signal. Just in case.

If you check all of this and the issue still persists, feel free to reach out and I am happy to assist you further.

expert reply by: Jesse M