I take it the "BOX" is a sealed unit ?...if it isnt take it apart and find out WHY it is dead an fix there if it a sealed unit I would do as you suggested and just jump around it, I dont see any reason it would hurt anything.
Ya just gottta love trailor wiring!...seems no matter what I do every spring is a chore in gettin them all workin again between the PA winter salt and weather ...its either the tow vehicle or the trailor that needs TLC.
Tim


1952 Chevy Shortbed

Photos in Photobucket

If It Aint Broke Fix It Till It Is!