Troubleshoot this electrical problem

[zac]

Daily driver K20 in decent condition. Ignition switch start function was getting close to failure, so I installed a start button low on the dash as a backup until I could either get a new column with a key or replace the switch. I'd noticed here that getting into the column usual gets pretty involved. But it was just a precaution, switch was still working fine.

Truck had been sitting 5-6 days, started up fine, but I immediately noticed a weird humming or buzzing from behind the dash in the area of the heater control. Then the Fasten Seat Belt light came on bright. It hadn't done much but blink occasionally in years. Hit the throttle to kick it off high idle and the belt light got even brighter, so I looked at the voltmeter. Pegged all the way past 18 to the right. Electrical smell, moved the heater and blower controls around an heard a pop. But it could have been a coincidence. Shut the truck off, went to start it again and it was dead. Headlight, park lights tail lights all work. Nothing else, not even brake lights or hazards.

It was dark and not at my house so I had very little ability to check it out before my wife picked me up. And I won't be able to get back to it for a week. I'm figuring right now it is the alternator, ignition switch or something in the heater control. Obviously a fusible link is gone, not sure which one as I couldn't get a good look and haven't had much time to go over wiring diagrams yet. If you have any input please let me know.

Thanks