When you say "Half" do you mean like
Marker lights, Tail, turn and such work but Indoor lights do not?
Motor homes have two 12 volt power systems. ONe for the MOTOR part one for the HOME part
Motor part may inlcude jacks and steps. It will include all exterior lights save for the porch and Work and any "Scare" lights you have (Basement lights are indoors) This includes Tail, Stop. Turn, Marker/clearance parking fog driving and headlights..
It may even include SOME lights inside (Dash lights and "Dome" light over the dash)
House is most all the indoor lights, Porch, Work and Scare.