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2005 Chevy Silverado 1500 and voltage drops to 12v after running…

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2005 Chevy Silverado 1500 and...
2005 Chevy Silverado 1500 and voltage drops to 12v after running a few minutes. I replaced the alternator but, that did not fix it.
Submitted: 8 years ago.Category: Chevy
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Answered in 3 minutes by:
6/24/2010
Chevy Mechanic: Tim's Auto Repair, mechanic replied 8 years ago
Tim's Auto Repair
Category: Chevy
Satisfied Customers: 16,247
Experience: Have owned a repair shop for 25 yrs.
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hi

the voltage regulator is built into these alternators..if the voltage is up around 14.3v then drops off to 12v or below after a while..i would think the problem is the alternator..load test the charging system with a load tester..if you don't have a load tester..auto zone and most parts stores will do this test for free

thanks

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Customer reply replied 8 years ago
No, I load tested the old one, replaced it just to be sure and even the new one load tests fine. it still drops off after about 10 minutes running. FYI, the battery is only about 3 months old too.
Chevy Mechanic: Tim's Auto Repair, mechanic replied 8 years ago

ok

when you put a load on the alternator..does the voltage drop?

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Customer reply replied 8 years ago
Yes, after the same 10 minutes or so.
Chevy Mechanic: Tim's Auto Repair, mechanic replied 8 years ago

ok

i would think the alternator is bad...do you have a set of test meters?or a volt meter?so we can test a few things?

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