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Old Mar 18, 2016 | 07:30 PM
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Default alternator not turning on

ive been having an issue with my alternator not kicking on when i start my car. if i rev the rpm's up to 2000 the volt gauge will go up to 14volts. i have also confirmed this with a meter. i bought a new alternator from Autozone and have the same issue with it. i unplugged the connector from the alternator and i have 10 volts on one red wire, 12 volts on the other red wire, and nothing on the grey colored one. once i unplug the connector and plug it back in the alternator will kick on then. im stumped. does it take a full 12 volts from the pcm to kick the alternator on? is the 10 volts not enough?
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Old Mar 18, 2016 | 08:29 PM
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as many here have found out it's a bad idea to replace the alt with a rebuild,these cars are very fussy about the right alt, and did you turn your old one in for a core ????
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Old Mar 18, 2016 | 10:01 PM
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Originally Posted by slider_buck
ive been having an issue with my alternator not kicking on when i start my car. if i rev the rpm's up to 2000 the volt gauge will go up to 14volts. i have also confirmed this with a meter...
Is this your original, OEM Valeo alternator? Was it fine before and this just began happening? This is typical behavior of a non OEM-equivalent replacement.

EDIT: trying to better help you, I searched your previous posts and found out your C5 is a relatively new-to-you, 6-speed 2002 with 80K miles, bought from a dealer, so it is possible your "original" alternator is not the EOM Valeo and it might not be an exact replacement either... Could you please verify that?

Originally Posted by slider_buck
...i bought a new alternator from Autozone and have the same issue with it...
As Akapounder just mentioned, the replacement you bought is not really OEM-equivalent. If your alternator was the original OEM Valeo, don't turn it in as core. It would probably be better to try to rebuild it. Check this post for more info.

Last edited by GCG; Mar 18, 2016 at 10:21 PM.
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Old Mar 18, 2016 | 10:28 PM
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Originally Posted by GCG
Is this your original, OEM Valeo alternator? Was it fine before and this just began happening? This is typical behavior of a non OEM-equivalent replacement.

EDIT: trying to better help you, I searched your previous posts and found out your C5 is a relatively new-to-you, 6-speed 2002 with 80K miles, bought from a dealer, so it is possible your "original" alternator is not the EOM Valeo and it might not be an exact replacement either... Could you please verify that?



As Akapounder just mentioned, the replacement you bought is not really OEM-equivalent. If your alternator was the original OEM Valeo, don't turn it in as core. It would probably be better to try to rebuild it. Check this post for more info.


the alternator that i just took off of it came from Oreileys Auto parts. I kept it because its farely new. I put it on the car just as soon as i bought it because that one wasnt wanting to put out 14 volts when it got a load put on it. Ive never had an OEM one on it.
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Old Mar 18, 2016 | 10:47 PM
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Perhaps you can try swapping the right regulator to see if that fixes your problem. Check the link I gave you in my previous post.
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Old Mar 19, 2016 | 07:06 AM
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Codes????????????


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Old Mar 19, 2016 | 08:43 AM
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currently no codes with it doing this. with the old alternator every now and then i would get a bunch of codes to come up. codes saying something about a short to some saying low voltage.
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Old Mar 19, 2016 | 09:53 AM
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Here is a link related to rebuild shops. We have no idea what year or tranny you have which affects the type for your car.

https://www.corvetteforum.com/forums...ternators.html


Mr. Sam
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Old Mar 19, 2016 | 10:45 AM
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Originally Posted by dadaroo
Here is a link related to rebuild shops. We have no idea what year or tranny you have which affects the type for your car.

https://www.corvetteforum.com/forums...ternators.html


Mr. Sam
its a 2002 6 speed. the alternator doesnt have the clutch assy on it
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Old Mar 19, 2016 | 11:02 AM
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Is it a 145amp or 110 amp? I have an extra brand new Valeo 145 amp unit.


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Old Mar 19, 2016 | 12:13 PM
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Originally Posted by dadaroo
...We have no idea what year or tranny you have which affects the type for your car...
Check Post #3 above. That information is already there.

Originally Posted by dadaroo
Here is a link related to rebuild shops...
He never had an original OEM Valeo in his car. The rebuilding path is not really for him. Check Post #4 above.
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Old Mar 19, 2016 | 12:20 PM
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Originally Posted by slider_buck
its a 2002 6 speed. the alternator doesnt have the clutch assy on it
The decoupler pulley is not used in manual transmission C5s
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Old Mar 19, 2016 | 01:30 PM
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Originally Posted by dadaroo
Is it a 145amp or 110 amp? I have an extra brand new Valeo 145 amp unit.


Mr. Sam

its a 110 amp. how much for it? i just returned the Autozone one.

Last edited by slider_buck; Mar 19, 2016 at 01:31 PM.
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Old Mar 21, 2016 | 10:57 AM
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im going to order a new alternator off of ebay. As long as i get a Valeo brand alternator i should be ok...correct?
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Old Mar 21, 2016 | 01:15 PM
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Replacement alternators and C5s are never a "sure thing". As mentioned above, this is well documented here... just search on the subject and you'll have a better idea of what you're dealing with.

Since you purchased your car without the original OEM Valeo alternator, you don't have its part number. It might be a good idea to look for it and use it as a double-check tool when searching for replacements. Be prepared for a trial-and-error process.

Perhaps you may want to explore the possibility of just replacing the voltage regulator with the right one and see if that does it (for 30 bucks). Check this post for more info.
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Old Mar 21, 2016 | 02:19 PM
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ive tried searching but never have much luck with the search feature on here. i never found that link you just gave me when searching for "alternator". thanks though. im going to buy a regulator and see if that will fix it.
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Old Mar 21, 2016 | 02:34 PM
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Let us know how it goes
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Old Mar 21, 2016 | 02:38 PM
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Old Mar 21, 2016 | 05:01 PM
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UNTIL you MEASURE the voltages on all the areas that you can prove the voltages are what they are suppose to be, its going to be a LONG EXPENSIVE JOURNY!

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Old Mar 21, 2016 | 08:26 PM
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Originally Posted by Bill Curlee
UNTIL you MEASURE the voltages on all the areas that you can prove the voltages are what they are suppose to be, its going to be a LONG EXPENSIVE JOURNY!


i did measure different points. i put that in my first message. when i start the car up im getting around 12 volts at the alternator lug, 12 volts on one of the red wires at the connector for the regulator, nothing on the tan colored wire, and 10 volts on the other red wire on the connector. the gauge inside also reflects this. when i rev it up to 2000 rpms i get 14.7 out of the alternator, 14.7 on the one red wire, not sure on the tan with it running, and still had 10 on the other red wire
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