2002 BMW 325 Alternator Charging, possible ECU

I have 2002 325Ci that will not charge properly. The alternator was bench tested at !13.2volts. On the the car it will generate more than 0.25volts. Using a digital multi-meter, the green wire with brown stripe (key on) produces the same voltage as the battery. The blue wire has ~ 1 volt less. Oh, when reving the car past 3Krpm, the generator will produce 1 volt and no more than 1 volt.

I'm presuming the blue wire is the exciter wire but am not sure. If this is the case, would the 1 volt drop be sufficient to prevent charging? And, what is causing the voltage drop?

Any ideas would be really appreciated as I've tried everything.