- You have probably fried a fusible link or two, as mentioned.
- You have probably fried the diode trio in the alternator. Rebuild time. jcappeljr, that's why you had the arcing when you reconnected the batteries, and why the old alternator fixed the problem.
beltfedonly, rebuilding these alternators is brain-dead easy, and not really expensive. You can buy a complete kit for around $60, shipped. That will give you new bearings, new electronics, and pretty much make it a new machine. Takes maybe a half hour or 45 minutes the first time through. I think it was Warthog who said he could do one in 10 or 15 minutes now since he's done a few. It's just really easy. The TM has a great section on it. The hardest part is taking it out of the vehicle and putting it back in.
You'll find some test procedures in the TM so you can verify the problem before you spend any money.
Parts
here. You should also order a
capacitor. The square one that comes with the kit doesn't fit our alternators.