New MH - battery drain question

Battery Boost will cross connect your house batteries to the engine to provide a jump start in the event the engine battery is dead. It may also permit you to use the engine battery bank to fire the generator. The Auxiliary on/off disconnects most of your draws from the house batteries when it is off - note MOST. To totally eliminate phantom draws you may need to disconnect the batteries at the terminal. As for showing 0 v on the house batteries. you should start with something simple like taking a volt meter and checking across the battery terminals. If that shows 0 you have a serious problem. If that shows reasonable voltage it indicates your gauge or some other item is the problem. Obviously if you don't have lights in the coach with the switch on it is also a sure sign there is no power coming from the battery bank to the system, but it still might be something other than the batteries.