[Fulltiming]

The "Master Lighting Switch" controls only 12 volt lights, no 120 volt. Check to be sure your house batteries are not drained down. It is possible the switch itself is bad but check the 12 Volt House Voltage on the power panel over the drivers seat. If it is up in the 12.2 volt or higher level, I would guess the switch. If the 12 volt house meter is reading less than 12, check the voltage of the starting batteries on the dash. If it is very low also, all of your batteries are drained. I don't know if you have power available where the coach is but if it is, plug in the coach and see if the house battery voltage bounces back up. Otherwise, your battery charger (or battery charger portion of your inverter) is either turned off or it is defective or you have blown the high current house battery fuseable link in the engine bay. Obviously, check the water level in the batteries and make sure the connections are tight and not corroded.

Hopefully you either have 120 volts available or the engine batteries are good enough to start the engine and recharge the batteries.