I think I found the problem, but it was nowhere near where I thought!
I fired up the chevy 4500 engine to produce 14.4 VDC from the alternator and started tracing that voltage back towards the RV house. The very first component downstream of the chassis battery is the item pictured below (the rubber cover says "Bussman").
With the engine started, on the left hand terminal, direct from the battery I read 14.4 VDC from the alternator. On the other side 12.63, the voltage on the house battery bank.
When I shut the engine off and test continuity between the two terminals it is an open circuit. Like a blown fuse. There are no part numbers on the Bussman device so how do I go about identifying and replacing it?
(Dang it, doesn't look like the pictures are displaying... try these links)
http://www.themeyergroup.org/bussman1.jpg
http://www.themeyergroup.org/bussman2.jpg
