One more possibility is that there may be a radio fuse in the Battery Control Center (BCC). Thr BCC is normally located in one of two places, 1) close to the house batteries or 2) in the storage bin on the drivers side just aft of the front wheel. It is a black box about 10" square and 6" deep. There are two lift latches on the box cover. Open the box and check inside. There are a number of fuses in the box for auxillary devices. In some, one is the radio fuse.
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