85 GT 3.4pr conversion. Alternator stopped charging, so I had it tested and it failed. New alternator also didn't charge. It tested good. The indicator light is on with key on engine not running and with engine running. There is very low or no voltage at terminal B on the alternator. BAT and A show normal battery voltage. The manual says volts should be between 2 and 4 at B. I've traced circuit to C500 and no volts for that wire (B3) there either. The fuse is good, the bulb is good. I don't know what to check next. Any help would be appreciated.
85 GT 3.4