Alternator Full fielding..??
There is no reverse. Doesn't matter which brush is on the supply side and which is going back to the regulator (green wire).
Key off. Take a multimeter set on resistance or continuity. Put one probe on the alternator housing and backprobe each brush terminal.
If they connect with ground, then its in the alternator or the wiring. Disconnect each field wire from the brush terminals. Check each until you find the one that's grounding.
If is not grounding with key off, then its probably a faulty regulator.
The regulator works by completing the circuit to ground.
