I've got a 92 Deville. I had a problem with the battery going dead. I had it tested and was told the battery and alternator were good. The starter was suggested. There have been quite a few times when I turned the key and the starter didn't engage, so I had known I was going to need to replace it. Well I did and the battery still went dead. I changed the battery and all was fine for a while. I went up town and the car died when I was slowing down for a turn. The lights dim when I hit the brakes and all the common bad alternator clues. I was wondering if it's possible for an alternator to test good and not be working right. Can an alternator fail intermittently? Any help is appreciated. I will replace it if it's bad. I have a winding sound when the engine is running and I think it's the alternator making the sound. Not sure of that though.