Diagnosing high voltage
Then it HAS to be that the green wire is shorted (to ground) OR there is a problem in the alternator.
Eliminating the VR, the alternator field is simply an electromagnet. From key--through harness--to alternator field on the blue wire--through the field--and the VR controls the "ground" or if you remove it and YOU short the field to ground (or something else does) then you have output. If you remove the ground and the field/ brushes are OK, it can not charge.