The wiring diagram seems to indicate the actual ground is that heavy dark wire that runs to the engine block. What happens when you clamp a test lead on that alternator terminal and run it to a known good ground? Do you get any dash warning lights?

If so, that's your problem. Bad connection either at the alternator or the engine block.

But from your previous note, that should be okay. I suspect there's something wrong with either the red wire or its connection to the alternator. I'd take it off and take a good look at it, and make sure that connection is tight and the wire itself is sound. With the key in RUN, do you have any voltage on that pole?