Alernator problems.

GALEGOR5

MEMBER
ISUZU

I have a 1996 Isuzu Trooper with 110000 mile on it. I had an issue with the alternator about 6 months ago. I switched it out and made a road trip about 800 miles and it stopped charging again. I then took the alternator back to the store where I got it and they were surprised it had failed. They replaced it with another. I put that one in about 2 months ago, and now it is starting to whine and it doesn't want to charge above 2500 RPM's. I can see the voltage drop from 12.5 down to below 10v. When I release the gas pedal the voltage comes back up to about 12.5. Do I need to get another alternator? Could there be another issue in the truck? I assumed that if there was a bad fusible link, changing out the alternator would have done nothing. Please help me out.

1 Reply

JAYRYDRE66

MEMBER
2 POSTS

1993 Isuzu Trooper 4WD, 3.2L V-6.
New battery, 2nd new Alternator.
First Alt. From local independant dealer "burned out" immediatly. Second Alt. From AutoZone, checked out good before and after installing, but still not charging. Incidentally, the alternator that was on the car when the problem noticed checked out good, but opted to keep new Alt.(Friend purchased car from a used car lot, drove approximately 3 hours, car died/ battery dead). Now when first start engine and release key, amps low on gauge, then a half second or so spike to around 14 amps, then down to 12 and under, and discharging. I've traced wires with no apparent shorts found, and keep trading out batteries so as to not completely drain his new one or my heavy duty one.
Can it be no 12 volt preload on the regulator, and how can I check it? Can I use a temporary jump wire from battery to Alt. Wire to check? Can it be the Ign. Switch? Or do I have to reset computer codes?