Good day- we just got our new to us 2004 Landmark Shenandoah home and am in the process of discovery. In the battery compartment there is a three part bus, a 12 volt mater disconnect switch, and then another small on/off rocker switch which activates what??? Any help would be appreciated. As this was a private deal and the PO only used it 4 times since 2004- he wasn't particularly helpful.