Question about 1999 Chevrolet Silverado 1500

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Alternator may be overcharging?

My Service Engine Soon light is on, and my Voltmeter reads 18 while the vehicle is running. I was thinking if this could be the alternator overcharging. I have a 1996 Chevrolet pickup truck 1500.

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Yes It sounds like the voltage regulator inside the alternator has gone wide open .It can also ruin your battery and explode the battery.I would have it hooked up to a alternator tester and just to make sure it's not just your gauge.hope this helps

Posted on Jan 24, 2009

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Well, 18 volts is an issue. And can cook your battery. Proper voltage range is 13.6 to 14.2 volts
The lower the voltage, the higher the amperage so 18 volts is doing nothing as far as charging but is doing alot towards ruining the battery. Have both checked. The battery could have wasted the alternator. good luck. I bet your battery needs lots of water. If so, it may already be trash.

Posted on May 12, 2009

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