what causes my battery to drain over night
Either you or someone could have left the ight on in the cabin by not closing the door......or there is a short that is draining it. Did you add any security system or a different set of speakers//radio recently? My son had a gent place a new set of speakers and the same thing happened to him.
Lastly I would check the alternator. i had one go bad on my truck and i charged the battery on it and tested it and everything and it was just the alternator
Your Grand Prix has battery run down protection. So it has to be something the computer can't "see" like was mentioned above. For example if I'm working on my 2000 model and have the doors or trunk open longer than 10 minutes the computer shuts down the lights in those areas. HTH. -Jim
Thank you it was the battery cables...
You're welcome. Glad to help. Thank you for letting us know and the best answer click! -Jim
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