When I measure the voltage, I am going from the D+ on the generator directly to the negative terminal of the battery.

I tested the ground of the generator by hooking to voltmeter between the battery positive & the generator ground (D-) & got the same reading as that accross the battery, so I assumed the negative was OK

I am pretty sure the amp light circuit it self is OK ... when I disconnect the lead from the amp light at the D+ of the regulator & hook it momentarily to the positive of the battery, it goes out. I am working from the assumption that the amp light is on whenever the voltage at D+ on the regulator is less than the voltage accross the battery - which would indicate that the generator is not charging the baterry. Since I have a negative voltage @ D+, the light is on quite brightly.

I can't figure out what I'm missing. It is as if the generator should be turning the other way, to produce a positve voltage.

I guess I could take the generator & the regulator to a shop as suggested, but they are both brand new/rebuilt (out of the Bosch box), so I am more inclided to send them back if I suspect they are faulty.

What is possibly the wierdest thing is that the battery doesn't seem to be discharging at all - it stays a a steady 12.2 volts & fired up 20-30 times today as we kept trying to figure out what was going on.