While I not directly familiar with your specific coach I do have some suggestions. Some coaches have a device that bridges (connects) the house and chassis battery banks if charge voltage is present on either side. Some coaches have different systems that may only connect on side or the other. One symptom of a failure is the house battery bank discharging with the engine running. To test this theory start the engine and let it run for at least 5 minutes. Check the battery voltage at the battery on both side. There should be less than 0.2 VDC difference between the two banks.