I'm showing that fuse 7 is for the radio, dash lights, cigar lighter, and interior lights.
If it is burning at the ignition wire, then there is a short to power some where. The task will not be an easy task to solve in thse case. You will have to go circuit by circuit to see whech one is causing the short to ground and creating the issue. I suggest starting with unplugging the radio followed by the cab interior dome light, cigar lighter, and then the dash lights.
I am attaching the diagram that Isuzu has. They don;t have much support for that year.
i wish there was an easier way for that situation, but there really isn;t. All that can be done is going section by section in this case.
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