Fuses blow when connected to Truck
I have a 2005 Jayco 27BH.
Everything works fine when the trailer is plugged into AC and the battery is connected. When I hook up my truck, the inline fuse at the battery blows and the "reverse polarity" fuse at the panel blows.
If I disconnect the battery while the trailer is connected to the truck, it's okay, and if I disconnect the truck and reconnect the battery everything is okay.
The connection to the truck is a factory molded connection (no screw terminals accessible) so I don't imagine that there are any crossed wires there. And, it's a relatively new truck (2011) with factory tow package that worked fine with my last trailer.
I checked the JB behind the battery to see if any of the connections from the truck or battery were loose or damaged, but everything looks okay. I pulled back the wire clamp to look for a pinch, nothing there. the JB is nice and clean, looks like factory, not tampered with.
Any troubleshooting ideas?