C4 Tech/Performance L98 Corvette and LT1 Corvette Technical Info, Internal Engine, External Engine

1985 Alternator Problem?

Old Dec 17, 2007 | 11:50 AM
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Default 1985 Alternator Problem?

My check engine light is coming on during acceleration, as my readout is showing 16 to 17 volts of charge. As soon as the rpm's go down, and the charge returns to a normal level (15 or below), the check engine light turns off. Is this most likely a battery issue, or a bad alternator? I believe that bad alternators usually result in a low reading, but don't know all the ins and outs. Thanks for any help.
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Old Dec 17, 2007 | 12:27 PM
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Why not just have both checked at your local Autozone? I do believe a bad alternator can over charge as well as under charge, but I'm not sure a bad battery can over charge.
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Old Dec 17, 2007 | 12:48 PM
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Does Autozone give you a free diagnostic check for the battery and alternator? Thanks.
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Old Dec 17, 2007 | 01:20 PM
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Either the alt is overcharging or your gauge is reading high. The average norm is about 13.7 to 14.1 Yes Autozone will test for free.
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Old Dec 17, 2007 | 03:05 PM
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Thanks.
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Old Dec 17, 2007 | 09:14 PM
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Probably your voltage regulator in your alternator runs out of control range when your alternator rpm is very high, I doubt a new alternator will fix this. Parts stores cannot run your alternator at the same rpm your engine can and your alternator will test ok.
Your battery cannot do what you see at high rpm, its your alternator.
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