When I bought my car off Jamie, the battery light was on but sometimes it would go off. I found out that there are diodes (4 I believe) in the alternator that can go bad and each diode spins and works at 120 degrees rotation.
Anyway, I drove the car for a few months like this, not knowing that the diodes were simply just going bad and finally, one day I started it and I noticed that the air ride acted like it was struggling to air up. I got about a mile down the road and then the light show got started. Everything on the dash started flickering off and on and then the car just died.
I bought a new 850/1000 battery from AZ over the phone (using my check card) and one of the workers brought it to me and installed it right where the car had died. I then had enough power to last me until I went to AZ and bought a reman from them with a lifetime warranty. I put it in and replaced the cracked 3 wire connector with a good one and that alternator lasted about 2 weeks and then it went bad. I took it back and got it replaced and haven't had a problem since.
O'Reilly's sells a reman under the name of Ultima and AZ sells one under the name of Duralast. In the 94 I had, I went through 3 Ultima alternators so I can safely say that they suck. The Duralast alternators are hit and miss. It might be junk out of the box and last a week or two and then again, you might get one that goes for years.
I do know that O'reilly's can get you a true Motorcraft reman with a 1 year warranty but AZ or Advanced can't.
If your battery light is off, it's charging and if it's on, it's not charging. Get the $40 alternator and have it tested and if it's good, install it and you should be fine, until it goes bad. Who knows when that will be?
The alternators in our cars can be killed with just a few WOT's because you're spinning them too fast. This goes for AZ and Oreilly's reman alternators but I have done many WOT's with the one I have now and I guess I got lucky with this one because it's still charging in the 14.? range but if and when it does go bad, I'll get another for free. I'm not saying that AZ has the best re-mans out there but they are better than the Ultima brand. I was burning them out and not doing any WOT's. I think the stereo system I have was killing them, idk.
So, if you can spare the $40, then get it and save up for a good one because what you have now has limited days before it's completely shot. The $40 might carry you for another 1 to 5 years. You never know and you don't know that the $40 isn't already a reman, which most likely it is.
Best part about it is that it is an easy alternator to replace. Like Chris said, it could be the voltage regulator but it is built into the alternator.
