"Full Field" Alternator Test

Thanks for all the input. I will test more tonight.....

OK, I think I have a problem... Got the trust meter out last night and with the key in the run position without the motor running I have 12 volts on both field wires on the alternator. If I unplug either field wire, I still have 12v on both terminals. Is this right? I started the car and using a screwdriver, it is "magnetic" near the bearing on the back of the alternator. Is my alternator shorted?

There is virtually no way to short the alternator stud to the field so that is not your problem.
Under no load, there should be 12 volts on both terminals. With no current flowing, there is no drop across the field. With that test you have confirmed that your brushes are in contact with the field at least at rest. It could change when in motion.
Short primer on how the regulator works: There is a constant 12 volts on one terminal. On the other terminal the regulator supplies a ground through a pass transistor on the regulator. The lower the voltage on the system, the lower the voltage on the field terminal it is connected. If there is no current flowing through the field, as Dayclona mentioned, there will be no magnetic field developed, no screwdriver attraction, no voltage generated in the secondary. Generally the failure of the voltage regulator is the failure of the pass transistor. It opens up. Rarely, it can short to ground making the alternator run at full current, cooking the battery. I have only seen that once in 40 years on a Volare police car.
If you hook one wire to the battery positive and one to the battery negative, the only thing holding the voltage down is the battery so depending on its condition, thermal runaway can occur and voltages well over 15 volts can be generated.
Craig

Last night I also disconnected both the blue and green wires on the alterator. From one of the post on the alternator I took it with a seperate wire to ground on battery on the other post i used another seperate wire and went to the postive post. With the car ideling, I still only had 12V across the positive and negative post on the battery.

change the VR.....with a NEW one

(1) voltmeter on alt case/stud (2) eng at fast idle (3) everything in car shut off (ex ign) esp light bulbs. (4) jump either male alt field terminal to batt neg then (5) jump other male alt field terminal to batt positive post for 3 seconds max. Read (& post) what you get for voltage & you'll hear (eng speed drops) the alt slow the eng down if it's charging.