Our's has a fuse located right at the coach battery presumably so that when all the battery disconnect switches are off this will still provide a direct link to a 12V source and therefore maintain the memory. I know this because I removed this fuse once and the radio went dumb.
John & Sharon, 2 Daughters, 2 Sons-in-law, 5 GK, 1GGK
Rat Terriers (Twiggy, Annie)
1997 HR Imp., 38CDS, 1 Slide
325 Cummins C8.3Mech., MD3060, EBw/Coast.Sw.,
Toad-2003 GMC Envoy 4X4, Excallibar TB, Pressure Pro TPMS, Henderson Mot. Ctrl. Units