It isn't in a fuse box. It is a fuse holder that runs off the house battery's. Take the cover off the house battery's and you will see a yellow wire attached directly to the battery. There is a single fuse block with a 15 amp fuse. If that is good there is another behind the radio which takes four screws to remove the radio. Hope this helps.
Thank you so much, we just returned home to NC, I took the battery box off and the fuse was fine, it appears the yellow wire fell off from the terminal, probably from vibration and also whoever installed it did not crimp the connector, works fine now..