Another "Charge System Fault" Question
Thread Starter
Le Mans Master
Joined: Oct 2007
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From: Akron Ohio
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St. Jude Donor '09-'10-'11
Another "Charge System Fault" Question
I know, I searched and didnt see something similar to mine. Most of the threads with these are from wrong/bad/different alternators, low voltage after sitting, etc.
Mine has been fine all year. Last two times I drove it to work (Monday and Today) I get the charge system fault message on the DIC when I start it. Its been cold in the morning, if that matters, but the gauge is charging at 13+ volts and no codes. On Monday I went out to lunch and also drove home. Both times during the day no message, just in the morning.
The car only has 40k miles and I am the third owner. It is the original alternator. I do have a 25% unerdrive crank pulley, but the system appears to be charging at 13.5v or better even with the headlights on in the morning. Is it still a sign of a failing alternator you think?
Mine has been fine all year. Last two times I drove it to work (Monday and Today) I get the charge system fault message on the DIC when I start it. Its been cold in the morning, if that matters, but the gauge is charging at 13+ volts and no codes. On Monday I went out to lunch and also drove home. Both times during the day no message, just in the morning.
The car only has 40k miles and I am the third owner. It is the original alternator. I do have a 25% unerdrive crank pulley, but the system appears to be charging at 13.5v or better even with the headlights on in the morning. Is it still a sign of a failing alternator you think?
Moderator, Tech Contributor
Joined: Sep 2013
Posts: 15,615
Likes: 4,061
From: Cape Coral, Florida
How old is your battery ??…if you have a DVOM and know how to use it I would suggest taking a voltage measurement of your battery AT the battery and then see what that voltage is before you start the car in the morning…also a good idea to have your battery load tested at your friendly auto parts store.
Thread Starter
Le Mans Master
Joined: Oct 2007
Posts: 9,700
Likes: 3,469
From: Akron Ohio
2025 Corvette of the Year Finalist - Modified
2024 C5 of the Year Winner - Modified
2023 C5 of the Year Finalist - Modified
2022 C5 of the Year Finalist - Modified
St. Jude Donor '09-'10-'11
It was brand new this spring, and the date on it when I bought it was only a couple months old. I made sure to look for the most recent one I could.
When I said it is charging over13v that is just according to the analog gauge on the dash. Would be a good idea to verify with a multimeter.
When I said it is charging over13v that is just according to the analog gauge on the dash. Would be a good idea to verify with a multimeter.
Melting Slicks
Joined: Sep 2008
Posts: 3,138
Likes: 802
From: Espanola New Mexico
If you are proficient with a DVM I would measure voltage at alternator output terminal and ground/negative and then measure voltage at positive battery terminal they should be very close to the same voltage, this would rule out the cable connections at the starter solenoid.
Thread Starter
Le Mans Master
Joined: Oct 2007
Posts: 9,700
Likes: 3,469
From: Akron Ohio
2025 Corvette of the Year Finalist - Modified
2024 C5 of the Year Winner - Modified
2023 C5 of the Year Finalist - Modified
2022 C5 of the Year Finalist - Modified
St. Jude Donor '09-'10-'11
Thanks guys! I will look into these things. I drove it a couple times this weekend without issue, but it was also warmer out. I dont know if that has anything to do with it. I will measure and clean when it goes into winter storage.
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Instructor
Joined: Jan 2022
Posts: 154
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From: Temecula, CA
Electricity and cold aren't friends. I'd suspect your charging system is otherwise fine, but there's a weakness in your system and the problem only manifests when it's cold. Whether that be the alternator, battery and/or possibly a bad/dirty ground.