[Ronbo]

The field coil will be referanced either to +12v or Gnd. From your input you have a single field connection. There were also isolated field alternators like the old GM units that had a "F" and "R" terminal.

You can check this by seeing if there is continuity to the output terminal (field is tied internally to +12v) or continuity to ground. (field is tied to case internally)

This will tell you what you would see from the reg output. (either a pull to + or pull to gnd to excite field coil)

You can verify the alternator (although it sounds like it's working) by disconnecting the field from the harness and putting a jumper on and touch it to +12 and gnd. to verify output. once you know this "bias" you know what the regulator should be putting out. **Warning do this briefly as when you slam full voltage across the field the v belt will likely start screaming under the load.**

Sorry this is so vauge but it's been some time since I delt with a external regulator system and they weren't real consistant among mfg's.

Is this the standard four terminal unit? (with case being gnd. conection)

I'll see if I can find some online references and look at mine to get a pin-out and what you should see. Also try a jumper wire from the block to the reg case to verify the wire harness isn't the culprit.