When I worked at a big truck shop (chip haulers and dump trucks) we would sometimes have a truck/trailer come in with a problem with the marker lights on the chip trailer.
after spending enough time to locate the obvious(plugs, connections and grounding of wires) we would take a 1/4 inch bolt and cut the head off. put it in place of the auto-resetting type fuse and wait for the smoke
Run new wires and the problem was fixed
