Yep they hook up the 2 wire plug on testing !
I put one off a 8 cyl , but same # as 3.9 6cyl in it.tested good an 14.1 . But we will see if does the same thing..

 

This is just a wag, but, I wonder if engine temp doesn't play a role? Maybe if the PCM thinks the engine is getting hot, it will turn off the alternator to lessen the load??? I know some of the newer cars will do this trick, but, no idea how far back that goes.

 

My 2001 most definitely does not do this.

Battery temp sensor could be a culprit yes; but since a physical whack fixes the issue, i'm still thinking it's field/core related.

 

Yeah, I'm gonna agree with ya on that one.

 

That replacement seems to be holding up fine..It must have been the diode or a short if it gets hot ..very odd to test good even on diode test [ but that's NOT when it's hot] .
Hadn't changed plug to it .
Glad it's not the pcm.

 

If the problem returns, check around to see if you have a local rebuild shop. You'll get a better rebuild from them than from the parts store. I'll only buy one from a parts store in an emergency now, if I have a few days it's off to the local shop for a rebuild.