I have a 4 pin trailer light system with submersible LED trailer lights. I have not had any problem until now. I noticed the last time I unhooked the trailer the smell of burning rubber. When I looked at the adapter that connects the trailer 4 pin to the 5 round car connection one point was melted and burnt. I looked at the trailer wires and the brown wires that is paired with the yellow wire has the insulation melting off roughly until about half way down the trailer. I have a 2004 Toyota 4Runner that it is plugged into. Is it a short in the trailer? Vehicle? or something else. Any advice would be greatly appreciated. I bought a new set of wires. Before I install them I would like to find the problem out first. Thanks in advance.