What's causing the running lights on my trailer not to work?

Just seeing if anyone has encountered this problem before or have an idea as to what is causing it.
My brake lights, turn signals, and flashers on the trailer all work but my running lights do not. There is a 15amp fuse under the hood of my truck that keeps blowing when I hook up the trailer wiring harness to my truck. The fuse is for the trailer running lights and as soon as I hook it up the wiring harness and turn on the lights it blows. Yet all the other lights still work. I imagine there is a short somewhere but I have no idea where. My trailer is a 16 ft. enclosed trailer..i have looked as best as I could and can't seem to find where the problem is.

 

had the same trouble with a Pace trailer after I put tires on it,the wire runs inside the fender and the tire grabbed it after going over a bump and shorted it out.

 

I had the same trouble when I tapped into the running light wire off the rear light pod of my tow vehicle. All those little running lights along with the running lights on the vehicle added up to pull more than 15 amps.
Once I hard wired the trailer plug to the fuse box we were good to go.

 

Had the same problem with my open trailer, the ground wire on the trailer had lost connection. Once it was re-grounded, the running lights worked.

 

Yeah sounds like a grounding issue to me. It is shorting out on the trailer body somewhere.

 

had the same thing happen to me w/ one of my trailers and all it was was the fuse from factory w/ the towing package wasn't strong enough to not blow every time i hooked up the trailer but since the brakes/turn signals aren't part of the towing package (they are connected to the harness for the truck) all of those still worked. checked and changed all wires and it never fixed it then went down to advanced and picked up a 20 amp fuse and haven't had a problem since. my .02

Ryan

 

Actually, I did try a 20 amp fuse and it blew that too.
Was working just fine for over a year (same truck/trailer combo) but it just started doing this all of a sudden.

 

mine had been working, then the ground wire on the trailer was pinched and not making connection. Once fixed the wire, lights worked again.

 

The frame of your trailer is ground. Look for a wire that has got pinched or the insulation has got worn through and the bare wire is touching the frame. Wrap it with electrical tape and have fun. My enclosed trailer was designed with the wires running through the frame and exiting under the frame at the rear. This happend to be the exact place that the trailer grounded out when exiting my drive way. It didn't take long for the harness to need some attention. I drilled a hole in the side of the frame and ran the wires out there to avoid a repeat.