We have a 2014 3570RS Bighorn. This unit has 2 outside power lets that are tied to the GFI in the bathroom. No matter what I plug into either of these (including a basic polarity tester) they trip the GFI. Nothing is damp around them, in fact they are both bone dry. I have other outlets on the same circuit. Any suggestions about where to start looking for the problem? We are on the road for 8 mo. so do not get to service centers.