Intermittent Battery Light

I have been having an intermittent battery light (charging) problem. I have replaced the battery, alternator - twice - (so that means three alternators in total) and the negative battery cable. I looked at the forums from previous people and put a volt-meter across the battery terminals. Before starting the car the battery voltage was 12.56. I started the car and the voltage stayed around 12V. No battery light on at this time.

Then I put the lights on and turned them to high beams. I also kicked the air on high. After a minute or two the battery light came on and the rpms went up and the battery voltage droped below 12V. The engine reved up and down a couple of times in no particular pattern and the light went on and off and eventually stayed on.

If I unplug the green connector from the back of the alternator, the battery light won't come on at all, so this must be part of the control to actually turn the light on if there is a problem with the charging system.

What does this green connector 4 wire plug do , control, go to, whatever? Is it possible that I have an intermittent open or short in the cable? Where does the other end actually end up? I tried to follow the cable but, it goes into larger and larger harnesses. It appears that the black cable with the spade end that is bolted to the alternator goes to the negative battery post. If this is possible, can I get this cable? and what is it called?

Thanks for the help. This is on a 89 Civic 1.5

What was your problem... it sort of sounds like mine? [email protected]

.... if a post is dead.. leave it that way.

Well, the problem ended up being another piece of crap alternator from AUTOZONE. I bought a used Alternator from a Honda Salvage yard with a 1 Yr. warranty and installed it nearly a month ago and haven't seen the battery light come on since! Problem solved! Don't get an alternator from Autozone.