mystery charging circuit ground or....other?

[David Pertuz]

A few months ago I replaced the alternator in my '96 G20 with a new Nissan one.

The other week I started getting flickering charge (battery+brake) lights.
Not fading in and out, as with a bad alternator, but either full bright or
off, occasionalyly coming and going, like a bad ground. Sometimes engine
movement, e.g. heavy acceleration, seems to bring it on (my mounts are
shot) and big bumps sometimes will too.

So....I checked all the connections. On the alternator, the plug is good,
main power node is good, ground lug is good. Ground on the pigtail to the
alt. bracket is good. Chassis ground behind battery is good. Only one I
haven't checked yet is engin-to-chassis ground.

With everything seemingly good....still the flickering lights. Tonight, for
the first time, I noticed, while accelerating at night onto the freeway,
that when I shifted from 2nd to 3rd, the lights dimmed as I went through
neutral. I replicated this once or twice, but it does not behave this way
on command. This suggests....voltage regulator?

I had thought it was just a bad connection somewhere, but I've just about
checked them all and they're all good (No DMM yet). And then there is the
lights-dimming thing, albeit only once or twice.

Am I missing anything?

thanks,
David