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1999 Deville
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Discussion Starter #1
OK, so all of this happened within a short period yesterday. Have a 99 Deville. First, I noticed that the A/C stopped putting out cold air, then the ABS light and traction control light came on with a message to check stability system. then on the way home, got a service sharging system message and I could see that the headlights were getting dimmer as we neared to house. After stopping the car, I could hear a kind of whinning coming from under the engine.

Any thoughts ?

Thanks, Michael
 

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Sounds like your alternator is going out. To check, put a volt meter across the battery terminals. With the engine off, you should read about 12.5 volts or so. With the engine running you should read approximately 14.4 volts, nice and steady. If the voltage is significantly lower than this, your alternator is probably shot. If it fluctuates up and down, then your voltage regulator is bad. Have you replaced the battery recently?
 

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I posted this someplace else too. When a bunch of random things go start going wrong, it's unstable voltages to the computer module. My cause of this was a bad cable, not alternator or battery.
 

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1999 Deville
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Discussion Starter #4
just got back from a trip. thanks for the tips, someone else had suggested the alternator. Here is the latest. I charge the battery and thinking it was the alternator, I drove it on short trips with everything off that I could (AC, stereo, etc) and the voltage was all over the place from 11.4 to 12.8. Then 2 days ago, I start it and it goes to 13.4 or so idling and when driving, it goes to 14.4 and stays there. I drive it on short trips leaving the AC off and the voltages read normal. Tonight, on a short trip, I turn on the AC and almost right away, it dropped to 12.4 and continued to drop to 11.9 by the time I got back to the house, about 30 minutes of driving. Any suggestions on this ?
 

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2010 DTS
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87,545 Posts
Between these voltage reading and the "whining from under the engine" my money is on the alternator.
 
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