12v Isolator Problem, Ford Chassis

[Daybreak97]

Do I potentally have an isolator problem on my 97 31 ft with ford chasis:

Parasidic drain for vehicle battery always...good for sitting only about a week before going below start level.

I have electronic vehicle battery charger/maintainer I hook up to vehicle battery while not using RV to keep veh battery charged so I can start vehicle.

Just noticed during rehab/repair of my coach that when I have 12v accessory plugged into rear bedroom 12v TV outlet (and coach converter is off or no shore power) that my maintainer is powering up, indicating bedroom outlet is drawing from vehicle batter, perhaps having drained coach battery....seems coach and vehicle batties are tied when ignition is off in vehicle...thought this would not be normal state?

[Gary RVRoamer]

Are you sure that outlet is not wired direct to the chassis 12v system and thus the chassis battery?

With no shore power and the maintainer off, check the voltage on the house batteries. Then check the chassis battery. If the voltage is always the same on both, the isolator may be closed.

[ImagineIF]

The house and engine battery banks may be connected when all charging sources are off. Depending on the isolator in use, there's a voltage threshold that must be met before the two battery banks are isolated.

[Daybreak97]

Thanks Gary and Gil. Thought of that 12V plug in rear bedroom being connected to veh batt, but thought no way...but who knows and a good first confirm or eliminate as possible explaination. Will use both you guy's ideas to further diagnose....Thanks! Will update thread in couple weeks when I can get back to my RV repairs.