Voltage Regulator and low output from Alternator

OK, sounds like a defective regulator OR MIGHT BE you have a shorted field in the alternator

Since this MIGHT be a problem, I'd be cautious. Might be worth your time to yank the alternator off there

You have a multimeter? Pull green wire

OFF AT THE REGULATOR FIELD

The reason for this is you do not want to disturb anything down at the alternator in case this is some intermittent deal. "You want to find the problem"

Post back if you have trouble. Set your multimeter up for LOW resistance measurement. Clip one meter probe to a GOOD engine block ground, and firmly stab the other probe into the green wire connector. You want to be CERTAIN you have a good connection for this. Carefully measure the resistance.

It should be MORE THAN a dead short.

The alternator field might draw (older) around 3A, or (newer) more like 4, and there has been reports of as much as 6 amp draw.

So using "one end" at 3A and the top end of 6A you can plug this into ohms law at 12V and this give you a resistance of around 4 ohms to 2 ohms

(R = E / I )

If it measures close to "a dead short"

Then either the green wire (unlikely) is shorted to ground

or the alternator has a problem. This is common with rebuilds, as common as having wrong or missing insulator washers in the brushes

IT JUST MIGHT BE that the field is shorted and has taken out your regulator. If this is so, remove the cover and see if you can find an open fuse inside. It might be an "open" piece of tiny wire