Why's my car making this sound once shut off?

2013 CHEVROLET IMPALA
175,000 MILES • 3.6L • V6 • AUTOMATIC
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DAVENOOB
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I think this sound is coming from the alternator. It's a high pitch whine. This video is 5 mins after running.
Dec 22, 2025 at 4:24 PM
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STRAILER
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That is a good one, I would disconnect the battery to see if the noise stops, and if so replace the alternator, thanks for the video it helps. Let us know how it goes, Ken
Dec 23, 2025 at 10:52 AM
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DAVENOOB
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Disconnected battery and sound stopped.
Dec 23, 2025 at 4:24 PM
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STRAILER
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Okay, remove the wires for the alternator and isolate them, then reconnect the battery to se if the noise is gone, if so replace the alternator.
Dec 24, 2025 at 10:00 AM
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DAVENOOB
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I have alternator on the way. I'll check that as well. Could a alternator problem cause other electrical issues? Dome light staying on, dummy lights on dash board? Thanks
Dec 24, 2025 at 10:11 AM
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DAVENOOB
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Oh ya it only did it after running will that test still work?
Dec 24, 2025 at 10:12 AM
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STRAILER
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Yes, this test will work and the bad alternator can cause problems if it is shorted internally or it had bad diodes. Let me know what happens after the new alternator is installed.
Dec 25, 2025 at 10:37 AM
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DAVENOOB
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Thanks. Merry Christmas!
Dec 25, 2025 at 11:43 AM
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STRAILER
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Merry Christmas!
Dec 26, 2025 at 9:22 AM
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DAVENOOB
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New alternator is on and working! No more whine. The dummy lights are still on, is it possible the bad alternator shorted something? Probably another issue all together.
Here's pic of the oil covered melted wire alternator. Wonder why it messed up lol.
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Dec 28, 2025 at 4:20 PM
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STRAILER
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lol, yep that is a bad one there. Nice work getting the problem fixed, please start a new thread for the warning lights, Thanks for the images :)
Dec 29, 2025 at 9:43 AM
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DAVENOOB
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Sorry for 2 email this is the email and thread. Didn't think to forward it the first time.
Dec 31, 2025 at 8:49 AM
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STRAILER
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No worries!
Dec 31, 2025 at 9:11 AM