do you mean the battery disconnect
yes that is controlled by a relay
that disconnects the battery from the main HOUSE circuits
be aware, that some circuits are never disconnects such a LP/CO detectors
also depending on the converter location and power center wiring
you will have 12v power, IF you are on shore power, even IF the batteries are disconnected, because the the house circuits are wired 'at the converter'
ans the converter is being powered by 120v shore power
the battery disconnect relay part of the battery control center is up front under the hood hatches,
in your case, I think on the drivers side
the inside switch is just 'signal' that tells the power relay to change
they 'lock' in position, ON or OFF, engaged or open
how many batteries do you have
previous owner might have wired everything to the engine battery and it does not always have a disconnect