Charge System Fault?
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Joined: Sep 2020
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From: Maryland
Charge System Fault?
I've had my 2000 c5 for almost a year now and put in a new alternator when I first got it. Fast forward to now, and I just started having problems with the voltage outputs. The other day ago the alternator went out and I tried to make it home but stalled out on the way. Last night I put a new alternator in it and it was fine for a little bit. Today I ran some errands with it and the voltage dropped and sat around 12.0 at idle and the alternator started whining. I've also been getting the charge system fault pop up every five minutes and have been reading code P1638. After looking everything up on here, it seems like a lot of people with the same problems have had a bad starter solenoid, but I have not had any problems with the car starting up at all. Anyone have any ideas on what it could be?
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Joined: Sep 2013
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From: Cape Coral, Florida
I've had my 2000 c5 for almost a year now and put in a new alternator when I first got it. Fast forward to now, and I just started having problems with the voltage outputs. The other day ago the alternator went out and I tried to make it home but stalled out on the way. Last night I put a new alternator in it and it was fine for a little bit. Today I ran some errands with it and the voltage dropped and sat around 12.0 at idle and the alternator started whining. I've also been getting the charge system fault pop up every five minutes and have been reading code P1638. After looking everything up on here, it seems like a lot of people with the same problems have had a bad starter solenoid, but I have not had any problems with the car starting up at all. Anyone have any ideas on what it could be?
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Joined: Sep 2020
Posts: 9
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From: Maryland
C5 alternators are really finicky in what aftermarket alternators are used !!...read the alternator “sticky’s” on the top of the C5 Tech section...best to have your old one rebuilt...as far as your whining alternator it may be some failed diodes...with a voltmeter check between the B+ of the alternator and the alternator case...set the DVOM to AC volts...should be less than .5 volts...I like to see .3 or less !!
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Joined: Sep 2013
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From: Cape Coral, Florida
The OEM alternators were made by a French company named Valeo...is that what you have now ??...before you start the car select battery voltage through the DIC and then start the car...my original OEM alternator voltage increases slowly increasing up to the normal charging voltage...does yours ??...read the alternator voltage between the alternator B+ and ground with some loads put on it...should be around 13.5 to 14.7 or so !!..and check that AC ripple for that whining !!
Last edited by C5 Diag; May 27, 2021 at 08:44 PM.
Thread Starter
Navigator
Joined: Sep 2020
Posts: 9
Likes: 1
From: Maryland
I believe I have the 130 amp alternator made in Mexico. The voltage after startup fluctuates all in the 12 volt ranges, and when rev it up it drops down into the high 11's. Also, I don't know what an ac ripple is lol.
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Thread Starter
Navigator
Joined: Sep 2020
Posts: 9
Likes: 1
From: Maryland
The OEM alternators were made by a French company named Valeo...is that what you have now ??...before you start the car select battery voltage through the DIC and then start the car...my original OEM alternator voltage increases slowly increasing up to the normal charging voltage...does yours ??...read the alternator voltage between the alternator B+ and ground with some loads put on it...should be around 13.5 to 14.7 or so !!..and check that AC ripple for that whining !!
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Joined: Sep 2013
Posts: 15,620
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From: Cape Coral, Florida
So I bought a multimeter and tested everything and all of the numbers looked normal. Another thing that's wrong with the car is that there is a lot of wobble in the harmonic balancer and it causes the belt tensioner to shake a lot as well. Do u think that could be putting too much stress on the alternator to cause it to produce the whine noise?