If you have a rear lighter and it works, the fuse is good. If you don't have a rear lighter or it too doesn't work, look for a 20 amp fuse under the hood and for a "cigar / accessory" relay.
I only have a '97 and '02 service manual. Somewhere between those years they changed where they get the radio's memory circuit. If your radio isn't working properly or maintaining the station presets and clock, that would also be a clue to a blown fuse.