smokin wire harness

2004 cherokee everytime i plug trailer lights in pig tail smokes up in the headliner center rear tried plugging in my buds boat same thing smokes what happened ? Doesnt madder whos boat it smokes short in wire or blown fuse why didnt my fuse blow .

You are going to have to isolate the wire, and check with a fuse diagram and see what is on that circuit. May have to take some interior apart and let the smoke out of the wire to trace it