Hello,

I am new to the forum and was wondering if anyone can help me. I have a 2007 diesel 2500 and all of a sudden my trailer lights stopped working. I have towed on a weekly basis since buying the truck and they have always worked fine. When plugged into trailers with good lights, in both the 7pin and 5pin, the only light to work is the rear right brake light.

Does anyone know what could be causing this?

Thank you,
Marc

 

On the 03's, the left and right blinker outputs each have their own fuse under the hood. Also note the smaller fuse (actually says PTC but I don't know what that stands for) that feeds both relays. That's the first place I'd look in your case since you lost both at once.

I haven't seen a newer shop manual to see what may have changed.

This is the 03 setup:

 

Thank you,
I am going to check that now.

 

If you do find that the fuses are bad then i would take a close look at all the connections on your trailer and make sure there isn't a crossed or frayed wires somewhere. Fuses pop for a reason. Simply changing them probably will only bandaid the problem until it happens again!