I know when I had my solar panels connected to the bus batteries thaat the not gen light would be on while driving so what it can tell you that charging voltage is high so regulator cuts out??
Yes, this is why I keep saying that alternate charging sources are the #1 suspect here. If you have a second charge source connected to the batteries, and that source brings the voltage up beyond the regulator's set point, then the regulator will turn the alternator field off completely. This will cause the Relay terminal voltage to drop to zero, and the Not Gen light to come on, because, literally, the alternator will be spinning but "Not Generating."
I guess I misled you in referring to my alternator as a 1 wire. I should have referred to it as a 24 volt alternator with a built in regulator (I consider alternators with built in regulators as "1 wire" alternators). My alternator has 3 terminals (BAT, Ign, and R).
Right, and I can see how you would make the Not Gen light work with that setup. But, in my book, a "one-wire" is literally that -- it has a single terminal post. I would call what you have an "internally regulated" alternator. I'm assuming Scott has just what he said: a one-wire, which means he would have no way to re-connect the Not Gen light to make it work.