Seabert41-
Welcome to iRV2!
1) Down by the floor, usually near the galley, is the propane detector. It has a green LED on it. Is the LED lit?
2) Also, if your coach still has a Norcold refrigerator, is the display on the Norcold lit?
These two devices receive 12V from the house battery bank by a path that's different than the house lights and the monitor panel. If they are powered, and the lights and monitor are not, then you should flip the BATTERY" switch by the front door and see if that fixes the issues. If a single flip does not restore 12V to the lights, do it once more, and then once more again. This is a simple check to preform.
After that, I'd start at the house battery bank, with a 12V test light or a voltmeter, and see where the 12V stops, as others have suggested.
On another topic, you should add a "signature" to your profile. It contains whatever info you want; most people put info about their coach there, so they don't have to type it into each message. Instructions for adding a signature are
here.
2017 Phaeton 40IH XSH Maroon Coral - Power Glide Chassis with IFS
Linear Mode
