With the engine off, key off, there shouldn't be any voltage at the stator terminal- the one next to the field terminal in the alternator plug. If you have voltage at that terminal under this condition, you have a shorted/leaking diode in the alternator. Some test rigs (and operators) don't measure output current adequately.
What current did you get from the alternator when it was tested? Is that output correct with the OEM specification? After-market suppliers tend to give a minimum output that sometimes is below the OEM specification.
Harvester
