No red idiot light for the charging system on a 240Z. Just the ammeter.

I did not know that. I have a 280. Thanks for the quick correction.

I think that the L terminal on a newer alternator still needs 12 volts, low amps, to power the windings immediately. It could be checked with a volt meter, with the key on, to verify. That's where I would start if I had this problem. If the L terminal is not getting power, then you can focus on the wiring. If the L terminal is getting power, focus on the alternator itself.

I'll stop now...

Does anyone have input to this post? I just did the same upgrade to my '73 and had the same result. My "cut in" is around 3,000 rpm. Other than that it seems like a nice upgrade.

That alternator eventually failed completely. I bought a replacement rebuilt alternator for an 82 maxima (i think) and no longer had that issue. I believe it had something to do with the "cut in rpm" of the alternator or maybe one of the diodes in the alternator had failed. Wish I could give you more information but as soon as I no longer had the problem I moved on to the next problem..... .

Just wanted to close the lid on this post- at least as far as my problem is concerned. After trying a few alternators and having the same problem, I checked the voltage regulator bypass plug and realized I had broken a tab off on it (the lower right one in case your interested). After fixing this the alternator charges immediately on startup with no revving required.

I now have a rock stable ammeter, solid headlights that don't dim at idle, faster blinking turn signals and a fan that spins stronger. I believe these are due not only to the higher amperage output but also to bypassing the mechanical voltage regulator. For $50.00 alternator and $20.00 for the plug this is a great upgrade.