I don’t have a relay. A wire runs from the battery to a switch at the door and back to the convertor compartment connecting to the fuses that supply power to the house, except the refrigerator whose power doesn’t go through the disconnect switch at the door. It sounds simple but the wiring looks complicated. A diagram of how your setup is wired would help us to help and probably de-mystify it for you as well. Some voltages at various places would clarify various things. For instance is there 12 volts between the two connections on the switch?
2004 E350 Adventurer (Canadian) 20 footer - Alberta, Canada
No TV + 100W solar = no generator needed