Which Internal fuse box? The W-22 has two chassis blocks, one combo and the house box.
I can help you with the first 3 only
Chassis Main: Under hood, front center, plain unmarked black box a retangular, latches on each side to remove cover, fuse legend inside, also two brass posts that have 30 amp fuses hooked to them but nothing else at bottom of unit, covered by cover.
Chassis AUX. near parking brake pedal under dash
Combo/house/chassis, (If you have one) To the right of the first one above, says Intelletec Battery Control on my unit,, which is why I say IF YOU HAVE ONE, this one contains fuses for house disconnect, Steps and some other circuits.
House box.. I can not help you since that is a complete body builder device.
Home is where I park it!