Monkey 456

I bought one of the 90 dollar wire harnesses for the camper and boat. went camping with the camper first. tail lights were funky. First the rights worked then the lefts but never both. Went anyway monkeyed with it for a wile and they started to work. Now three weeks later I take the boat no camper and all I have is running lights. The truck lights work fine bot nothing off the too plugs.
What gives?