enblethen is right.
Hopefully this will put the nail in it:
"Battery Changeover" on the schematic is the rocker switch. I have labeled MOM and DUAL. The center common wire goes to the Charging Solenoid (they call it Battery Solenoid).
When in MOM, it's pretty simply - the Aux Battery (House Battery) is routed to the Charging Solenoid and gangs the batteries together. Done deal.
When it's in DUAL, power comes from the "Fuse Panel". This is a 4-pin yellow plug that simply plugs into a spot on the OEM vehicle fuse bus panel that is hot when the key is in RUN.
That's it.
All the rocker switch does is energize the Charge Solenoid either from the House battery (MOM), or from a RUN hot circuit in the vehicle fuse panel.
Steve
