I own a stock 89 CRX Si.

Recently my vehicle has been acting very funny. It seems as though the alternator suddenly and inexplicably shuts off when I let the car idle. This usually only happens when I let the car idle after freeway driving. I hooked a volt meter to the battery to watch the electrical systems voltage as I drove to and from work. What I found startled me...

The major thing is that the warning light is not always on when the alternator is not outputting. It seems that the light only goes on at idle even though the voltage is down around 12v.

The other is that when the electrical system is low (battery voltage), it ALWAYS jumps back up to 14 volts the moment I hit 45mph. It doesn't matter what gear I'm in, or what the engine speed is. The moment I accelerate to 45, it jumps back up...

I had my mechanic check everything out, and short of changing out the ECU (not one available), nothing has helped. We've tried 3 different alternators with no positive results. We checked all the wiring, and even tried replacing the Electronic Load Detector (engine bay fuse box), and nothing has helped...

The only things we haven't tried yet are replacing the ECU, and replacing the battery.

Do you guys have any insight on this? Perhaps some things I can check out this weekend...

Thanks

 

edit**** 9/28/2011

Problem turned out to be the crappy checker auto parts (now O'Reilly) alternators. It finally died on me a few months ago. I had been living with the charge warning light this entire time. When I swapped in a lifetime warranty Autozone alternator, the problem was gone. Hasn't come back since. Autozone seems to have better quality stuff IMO.