1998 Pontiac Grand Am

1998 PONTIAC GRAND AM
147,000 MILES • 6 CYL • FWD • AUTOMATIC
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EVO9393
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  • 2 POSTS
start up ok 2 minutes later battery light comes on. replaced altenator ,battery and checked the grounds.getting 11.80 on voltage from alt to battery. when running its 7.68,. replaced altenator again ,same problem. thank you , moe
Feb 9, 2008 at 5:23 PM
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MASTERTECHTIM
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  • 4,750 POSTS
moe you need to check the fat red wire at back of alternator for battery voltage, sounds like you might have no power there. check back to us.
Feb 9, 2008 at 5:38 PM
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RASMATAZ
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Those readings are just too low- for the engine management to operate properly-The field ciruit is computer generated-in other words the computer acts as a voltage regulator. See below


https://www.2carpros.com/forum/automotive_pictures/12900_alternator_4.jpg

Need more help don't hesitate
Feb 9, 2008 at 5:44 PM
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EVO9393
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do i replace the computer? this is the closest ive been yet lol
Feb 10, 2008 at 9:44 PM
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RASMATAZ
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This is where I stop-If all checks out -the Alty,Battery, and all connections are cleaned and properly connected/tighten.

The computer is the last place I tell the customer to go-its not cheap-especially if there's a wire problem and you hook up the new computer and get fried in sec or 2. Your shot!

Go to an indepedent shop and have them take a shot at it with their machines_
Feb 11, 2008 at 12:03 AM