The other night my battery light came on at the same time a loud squealing started in my engine bay. Easy to diagnose, so I checked the alternator. It looked like the belt had loosened up, so I retensioned the alternator belt and voila, the battery light went off.

Out of curiousity while I was driving the car I hooked up my Bluetooth adapter to check the voltage, and it was jumping all over the place, both at idle and while cruising. Lowest reading I had was 11.2v and the highest was 15.9v. Can't be a good thing.

As I drove the car home, I noticed the car would miss right around the 2k rpm mark and my headlights would dim at about the same time. When I pulled into the driveway and turned the car off the headlights got very bright and then everything went dead. No power to the interior lights, headlights, windows, radio, starter, nothing.

So I figured that while my alternator belt had been loose, the battery had been drained to the point where nothing had power. But having experienced a draining/ed battery before, I know it's not a sudden power loss, but a gradual one (lights dimming before going out, etc.) So this makes me wonder if this is the voltage regulator going out rather than my alternator.

Also, after coming back to the car an hour or so later, it looks like there is a very tiny charge coming from the battery. The interior lights come on when I open the door, though they're very faint.

I don't mind buying an alternator, it's about time, but I don't want to buy one if my voltage reg. is going to kill it soon after. Do these symptoms sound like the alternator, or the voltage reg?

The voltage regulator is internal to the alternator and switched by the ECU.

Replace the alternator.

I'll double check my info, but I thought I read that the regulator was part of the ECU. If it's part of the alternator, then that's great.

Yeah, I'd go with Dino also. I was still on my original alternator from 99 and the pully bearring(not the belt) started squeeking at certain times...got really bad and embarrissing. I just changed it last week. I was also wanting to get the exact same alt. that came with the car when it was built from the factory because it lasts so long. You can't get it from the dealer, however, you can get it from a place called vintage parts.

http://www.vpartsinc.com/

part number 4661998 under Chrystler Motor Corp.

It's a little pricey but it's the exact same one that came with the car when it was built. I'd rather go this route then buy aftermarket that's only going to last a few years.

Originally posted by DarkOne
The voltage regulator is internal to the alternator and switched by the ECU. Replace the alternator.

Assuming this is correct, how do I know if the regulator itself is dying, or if the ECU is going?

Annnnnd it was the alternator. Swapped in a new (not reman'd) unit and voltage is a steady 12.8 volts @ idle. Thanks fellas.

Sure man.