I'm not exactly sure yet but I recently bought 2 running light assemblies and installed them on the trailer. Each assembly had 2 short wires already attached but I didn't use them. I left them hanging and I think that they are probably touching the trailer and causing the fuse to blow.
I'm gonna change the fuse and try to blow it by touching the bare wire to the trailer. If that works I will tape the wires, change the fuse, and that should do it.
Thanks for asking and keep your fingers crossed for me.- Brad Baker