Sorry, I've been under the weather and missed this post. If you have not already done so, I would contact Fleetwood in Decatur and get the wiring schematic for your coach. If you give them the FIN number they will email you the wiring schematics which should help.
One of the most common issues we see is poor grounds. The constant care and cleaning of all the connection points around the batteries can help alleviate a lot of issues.