the switch may be labeled AUX or BATTERY BOOST or similar, or may not even have a label at all...
also, look in your battery or inverter bay - see if you have a 12v D.C. coil by Trombetta, or WhiteRodgers, etc.... which may indicate you have one... or it could even be in your engine bay, mounted on the sidewall.
'14 Thor Palazzo 33.3 compact diesel 100k+miles since '14... US, Alaska, Canada...
AND a '14 Gulfstream Amerlite
AND a '07 ForestRIver Rockwood