Extremely High Voltage reading?????

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Jun 22, 2009 | 05:22 PM

SilverStang00

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From: Georgia

Extremely High Voltage reading?????

I am very confused on this one guys. Electrical systems always go over my head so any help y'all can provide would be awesome.

I recently had an ASP underdrive pulley set put on my 98 SS. I have noticed that when driving the car the voltmeter will increase/decrease drastically. Normal accelerating from a dead stop will raise the voltage to around 17ish on the gage(the highest it goes is 18). Once the car gets up in speed and shifts into overdrive the volts will decrease back to around 12ish(13 is the middle marker) or so.

Any ideas on what could be causing this? The U/D pulley? Alternator? I did a search and all I could find is instances of people losing voltage not the other way. I would be very much appreciative.

Jun 22, 2009 | 05:28 PM

Lickeyman

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From: Georgia

Probably broke the exciter wire on your alternator or it's going bad.

Jun 22, 2009 | 05:31 PM

SilverStang00

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From: Georgia

Quote:

Originally Posted by Lickeyman

Probably broke the exciter wire on your alternator or it's going bad.

Could you expand on that some more? Sorry Im not well knowledged when it comes to this sort of thing and Im trying to learn as I go. Thanks for your reply

Jun 22, 2009 | 05:38 PM

Lickeyman

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From: Georgia

98's (and I think 99s) have an exciter wire that is really easy to break if you pull the alternator.

Also a lot of the time if an alternator is going bad it can overvolt. Mine did that. It would actual overvolt to 18 and bounce. Annoying as hell.

Jun 22, 2009 | 05:44 PM

SilverStang00

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From: Georgia

Quote:

Originally Posted by Lickeyman

Gotcha. Thanks man.

What would be the easiest way to tell if the alternator is going out? Pull it off and have it tested?

Jun 22, 2009 | 08:27 PM

OUTLAWZ RACING

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From: COLUMBUS GA.

Yes or take off the neg while the car is running and if it shuts off 90% of the time its your alt.

Jun 23, 2009 | 05:57 PM

NBM99SS

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From: St. Louis

Quote:

Originally Posted by OUTLAWZ RACING

Yes or take off the neg while the car is running and if it shuts off 90% of the time its your alt.

Do not do this. This does not work on OBDII cars. It can do damage to several electrical components. This test works on older cars just fine.

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Jun 23, 2009 | 10:22 PM

PKC-Z71

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From: Lee's Summit MO

Quote:

Originally Posted by SilverStang00

Gotcha. Thanks man.

What would be the easiest way to tell if the alternator is going out? Pull it off and have it tested?

Hook up a voltmeter to the battery, and with the car running see what it's reading with NOTHING electrical turned on. Then turn EVERYTHING electrical on while the car is running, and see what it reads. You'll probably have to raise the RPMs up a little bit to get a true reading, since you have underdrive pulleys on it- some cars are known to discharge at idle due to underdrives, that's just part of the deal with them. As long as the alt. charges OK at just above idle and up that's really all that matters.