I installed a Fiero Store Power Pulley on my '85 with the 3.4L v6 and now my alternator does not charge, it was working fine before I installed the pulley, maybe it's just simply belt tension.... I have 2 alternators on hand and I have had them both recently checked over by a local shop (within a week) and they were working very good.

I pulled the one out that was in the car and installed the other and still no charging.

I cleaned all of the terminals really well and actually put a new connector on the heavy red wire for the battery. I know that the 2-wire plug is sitting well on the correct spot and making good contact.

I tested resistance between the alternator lug and the battery lug and got 0.3 ohms resistance. That cable is good.

The battery light comes on when you turn the ignition on and stays on after the "bulb test" circuit does it's thing.

What could be causing the alt to not charge? What do the two wires on the alternator do? I know that one is connected down a few inches on the battery wire, but what does the smaller brown wire do?

Also, is there a way to do a diode check with a digital multimeter?

Thanks!!

------------------

Club Redline - Northern Minnesota Sport and Modified

[This message has been edited by Oslo (edited 09-11-2007).]

I don't know if it matters so much but which type alternator do you have, the SI or CS?

whichever is the early style.

Have you checked if the alternator is going into full field on its own or not?

Ogre's Cave has a couple good articles on the older SI versus the new CS type alternators. Also has some interesting info on the Power Pulley you installed. Did you rev the car to spin the alternator enough to get it excited? The CS swap is really easy and gives more juice......

The brown wire goes to the charge indicator light and the gauge. It goes through the C500 first of course.

quote Originally posted by InaneCathode: Have you checked if the alternator is going into full field on its own or not?

Sorry but I don't know what that means.

I watched my DVOM with the vehicle running and revved it up to 3K or so and still no change in alternator activity. I'm going to toss the old pulley back on and see what happens then.