Electrical Help Needed - Big Time

You can troubleshoot this easy

Start the car, alternator hooked up, and diddle with the idle screw until the charging voltage is around 13-15. You want it high enough to troubleshoot, low enough to "not hurt" the system/ battery

Pull one field wire off at a time, and make sure that EACH time you do this, it quits charging. Switch the field wires at the alternator and repeat. If this is OK, the wiring is probably OK. It would not hurt to pull the connectror off the regulator and make sure THAT stops it from charging. If that's OK.......

Now stick one probe of your meter directly onto the battery negative post, the other probe directly onto the regulator case. Make sure you "stab" it into metal. You are looking for a VERY low reading, zero is perfect, you don't want over .2V (two tenths of a volt) Higher voltage means the regulator is NOT seeing the battery ground.

If this is OK, check the hot side. Stab one probe directly onto the battery positive post, the other probe as close as you can to the regulator IGN terminal. Probably the key side of the ballast resistor is OK, (dark blue.) Once again, you are looking for a very low reading.

If all the above checks out, and the battery is OK, replace the regulator.