We recently purchased a 1988 Catalina Ford E350. The monitor panel inside just above the entry door does not display anything. It should show us water levels, LP level and battery level but we can't figure out if it has an on/off switch or if it should display something all the time. The manual we got with the motorhome just tells what the "typical" monitor will do and that "your dealer will be happy to explain", but there is no longer a local dealer. Does anyone know? Thanks.