d.
Alternator clutch
Thread Starter
3rd Gear
Joined: Aug 2012
Posts: 3
Likes: 0
Alternator clutch
Ok guys I am sure this is an old question so here it goes. I have an 04 with auto trans, as long as it is cool outside it does mater how long I am in idle with all acc's going, but once it is hot out side and Florida summers 95 is normal, and the car has been running for a while my voltage drops at idle from 14 to 12 volts. Is this problem the alternator clutch that is attached to the front of my pulley? If it is can I run an alternator without the clutch on it, this would be my second alternator change for the same problem.
Instructor
Joined: Jun 2010
Posts: 228
Likes: 2
From: California
Alternator clutch? Haha! Never heard of that one before! The alternator has no clutch. Maybe your idle voltage drops when its hot because your cooling fans are on. Maybe their running too much. Check for debris up in front of radiator.
Tech Contributor
Joined: May 2008
Posts: 3,100
Likes: 17
From: Somers, CT and Clermont, FL
St. Jude Donor '09-'10-'11-'12-'13-'14-'15-'16
A4 equipped C5's, beginning in 2001, DO have a clutch attached to the alternator pulley. It's used to prevent a slow idle or stalling while stopped, when the transmission is in drive.
Tech Contributor
Joined: Jan 2007
Posts: 19,239
Likes: 1,091
From: Dyer, IN
Just because you do not know about it, does not mean it's not true. Quicksilver Vert 01 is absolutely right. The technical name for the part is a "decoupler pulley", and it was part of TSB #99-06-04-029A
Le Mans Master
Joined: Mar 2011
Posts: 6,835
Likes: 301
From: Columbia SC
You can use a C5 alternator with or without the decoupler. The size of the pulleys is identical and use the same serpentine belt.
I don't see that you have a problem since from what you have said it seems like the alternator decoupler is doing it's job. "Be happy, don't worry."
Quicksilver Vette 01 is correct for the reason they started using the decoupler.
I don't see that you have a problem since from what you have said it seems like the alternator decoupler is doing it's job. "Be happy, don't worry."
Quicksilver Vette 01 is correct for the reason they started using the decoupler.
Tech Contributor
Joined: May 2008
Posts: 3,100
Likes: 17
From: Somers, CT and Clermont, FL
St. Jude Donor '09-'10-'11-'12-'13-'14-'15-'16
The next generation of GM alternators uses an even more sophisticated system called RVC, which stands for Regulated Voltage Control.
I origionally thought that I had charging system problems with my new 2010 Silverado, until I became familiar with the operation of RVC.
Although it doesn't specifically mention 2004 Corvettes having a RVC charging system, in the GM tech bulletin link below, the OP described a very similar mode of operation in his post.
http://www.archivedsites.com/TECH_CO...05%20Final.pdf
Last edited by Quicksilver Vert 01; Aug 28, 2012 at 12:13 PM.
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Instructor
Joined: Jun 2010
Posts: 228
Likes: 2
From: California
...and you make that statement with such confidence...... Just because you do not know about it, does not mean it's not true.
Yes I did say it with confidence. Iv' e been a mechanic for 40 years. I work on locomotives now. Worked on every car you can think of including many Corvettes. And I have never seen or heard of an alternator clutch. And my 99 C5 doesn't have it of course. To me it was like the joke about the muffler bearings.
Yes I did say it with confidence. Iv' e been a mechanic for 40 years. I work on locomotives now. Worked on every car you can think of including many Corvettes. And I have never seen or heard of an alternator clutch. And my 99 C5 doesn't have it of course. To me it was like the joke about the muffler bearings.
Tech Contributor
Joined: Jan 2007
Posts: 19,239
Likes: 1,091
From: Dyer, IN
...and you make that statement with such confidence...... Just because you do not know about it, does not mean it's not true.
Yes I did say it with confidence. Iv' e been a mechanic for 40 years. I work on locomotives now. Worked on every car you can think of including many Corvettes. And I have never seen or heard of an alternator clutch. And my 99 C5 doesn't have it of course. To me it was like the joke about the muffler bearings.
Yes I did say it with confidence. Iv' e been a mechanic for 40 years. I work on locomotives now. Worked on every car you can think of including many Corvettes. And I have never seen or heard of an alternator clutch. And my 99 C5 doesn't have it of course. To me it was like the joke about the muffler bearings.
Instructor
Joined: Feb 2012
Posts: 102
Likes: 2
FWIW OldHorsepower, I consider myself mechanically adept, and I've worked on plenty of modern cars, and I've never bumped into this one, either. Compressor clutches, sure, but not alternator.
Just curious, if anyone can tell me...does an alt clutch default to engaged with no power, and disengage when switched on? I'd expect this, since otherwise you will need to use power to run the alternator...also, does it disengage at WOT?
Anyway, if you'll excuse me, I have to get down to the store to get more turn signal fluid. I'm almost out!
Just curious, if anyone can tell me...does an alt clutch default to engaged with no power, and disengage when switched on? I'd expect this, since otherwise you will need to use power to run the alternator...also, does it disengage at WOT?
Anyway, if you'll excuse me, I have to get down to the store to get more turn signal fluid. I'm almost out!
Safety Car
Joined: Jan 2012
Posts: 3,953
Likes: 520
From: Da U.P.
Huh, I knew they were a thing but had no idea C5s came with them. I thought the RVC predated the clutched pulley though, my 98 GMC K1500 has a PCM controlled alternator. I bet if I pull the tune on my 04 M6 it has that as well. My gut tells me the clutched pulleyed cars had both. It's either an L or F (or both?) terminal on the alternator.
