Electrical problem
1990 Other Isuzu Models 4 cyl Four Wheel Drive Manual 184000 miles
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Thurs morning truck started OK. At lunch battery was dead. Suspected I left lights on, but did not. Jumped car and it ran OK rest of day. Near home, the heater/A/C blower (fan) ceased to work, A/C quit, and the dashboard warning lamps all came on. I got home, and shut it off. After a few minutes I tried to start it. It ran for about 4 seconds and died. Tried that a couple of times, and it would not run. I opened hood and smelled burnt electrical components and determined alternator was at fault (I replaced Isuzu OEM alternator 4 yrs ago with remanufactured unit). Battery is a 3 month old DIE HARD GOLD. Anyways I pulled the alternator and replaced it with a new (remanufacured one from Checkers..brand = Autolite). I put the battery on a 6/2 am charger, and went to Checkers and got a new alternator (which I installed today). I then cranked the engine, it started and the BRAKE, LOW FUEL (truck is not low on fuel as it has half a tank of fuel) and BATTERY warning lamps are illumniated on dash (still). The "Check Engine" was NOT lit. I went to Sears, then Checkers (to get two diagnostics) and the battery was verified as good (and charged) and new alternator was verified as good (charging 13.7V, diodes and so forth all check out fine). I pulled the battery cables off again to see if that would clear issue, but no go. There is no short or drain on any circuit (tested this as well before I quit for the night). The heater/AC blower is stilll out, and when the A/C button is engaged, the A/C clutch does not engage on the A/C compressor pully. I thoroughly checked both fuse blocks for blown fuses relating to A/C and blower motor and the fuses all check good.

What is causing this problem?