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Old 07-15-2006, 01:47 AM   #1
kornphlake
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Default Depressing clutch causes voltage drop

Okay this one's got me puzzled. I've noticed over the last few weeks that the little battery icon on the instrument panel has been flickering on and off but the car has always started so I'm not too concerned. It finally warmed up enough to use the AC this past week so I've been driving home with the AC on HI, yesterday I noticed at a stop light that the AC blower had slowed down and the icon on the dash was lit indicating that the voltage was low. I shifted into neutral let off the clutch and revved the engine and the blower started making a normal amount of noise and the light on the dash went off. At the next signal I noticed that keeping the clutch depressed and revving the engine didn't revive the blower and the light didn't go off, by the third signal I realized that the light came on every time I stepped on the clutch to shift and when I was waiting at a stop light regardless of rpm.

My first thought was that maybe the clutch is going out and while idling at a stoplight with the clutch depressed there's enough drag to bog down the engine enough to drop the current from the alternator. The wierd thing is that with the transmission in neutral pressing on the clutch will raise the RPM about 150 RPM momentarily, releasing the clutch will cause the RPM to drop about the same amount momentarily. It seems like the clutch is working just fine and the RPM fluctuations are from the drag caused by the tranny in neutral.

Any ideas why the clutch would cause a drain on the electrical system? There's not an electric clutch booster pump or something tucked away somewhere that I don't know about is there?
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Old 07-15-2006, 01:58 AM   #2
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Default Re: Depressing clutch causes voltage drop

When you stepped on the clutch to shift, you were also (hopefully) off the throttle. The resulting DROP in engine rpm making the alternator spin corresspondingly slower and hence produce lower electrical output. REPLACE the alternator, you are living on borrowed time.

NOTE: This advise assumes:

Battery is not feeling its age
Belt and belt tensioner are in good shape and belt is therefore not slipping
Battery cable connections, including those at the STARTER are clean/good/tight.
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Old 07-15-2006, 07:16 AM   #3
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Default Re: Depressing clutch causes voltage drop

I'll second what Wolfman said. You are living on borrowed time. This one left me stranded on the side of the road once.
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Old 07-16-2006, 08:41 PM   #4
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Default Re: Depressing clutch causes voltage drop

I'd normally agree that it's the alternator, but I with the transmission in neutral I can rev the engine to 3k RPM and the icon on the dash will turn on whenever I put my foot on the clutch without letting the RPM drop. Additionally as I described, with the transmission in neutral at an idle, when the clutch is depressed the light comes on, then goes off when the clutch is released. Unless the clutch somehow talks to the alternator I'm thinking it's not the alternator.

I know there's a switch that turns disables cruise control when the clutch is depressed, I'm wondering if maybe there's a short somewhere in that circuit. I don't think it's the safety switch behind the clutch pedal that senses the clutch is fully depressed to enable starting because I don't have to push the pedal to the floor to get the light to come on.

I just don't want to spend money on a new alternator just to find it is something a butt splice or wire tie could have solved.

I forgot to mention in the original post...

96 SL2
154K mi
Manual tranny (obviously)
No mods or upgrades
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Old 07-16-2006, 09:05 PM   #5
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Default Re: Depressing clutch causes voltage drop

Quote:
Originally Posted by kornphlake
I'd normally agree that it's the alternator, but I with the transmission in neutral I can rev the engine to 3k RPM and the icon on the dash will turn on whenever I put my foot on the clutch without letting the RPM drop. Additionally as I described, with the transmission in neutral at an idle, when the clutch is depressed the light comes on, then goes off when the clutch is released. Unless the clutch somehow talks to the alternator I'm thinking it's not the alternator.

I know there's a switch that turns disables cruise control when the clutch is depressed, I'm wondering if maybe there's a short somewhere in that circuit. I don't think it's the safety switch behind the clutch pedal that senses the clutch is fully depressed to enable starting because I don't have to push the pedal to the floor to get the light to come on.

I just don't want to spend money on a new alternator just to find it is something a butt splice or wire tie could have solved.

I forgot to mention in the original post...

96 SL2
154K mi
Manual tranny (obviously)
No mods or upgrades

If this is the case then have a look at the clutch pedal area under the dash. Pay attention to the wiring harness that is by the clutch pedal pivot area. hard to get hard to see but it is there at there very top of the pedal. They can rub through and begin to start shorting out wires.
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Old 07-16-2006, 10:30 PM   #6
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Default Re: Depressing clutch causes voltage drop

Quote:
Originally Posted by kornphlake
I know there's a switch that turns disables cruise control when the clutch is depressed, I'm wondering if maybe there's a short somewhere in that circuit.
There is no such switch. If you're certain that it's not the starter interlock switch on the floor, I would second the recommendation that you look for wires being pinched/scraped/whatever by the clutch pedal as you apply it. In any event, if your battery light is on at idle, your alt is probably on its way out anyway (or perhaps your serpentine belt is slipping).
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Old 07-16-2006, 10:40 PM   #7
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Default Re: Depressing clutch causes voltage drop

Thats a tough one man. The only advice I had was already said. Please let us know if you find the problem man good luck on the problem hunt.
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Old 07-16-2006, 11:02 PM   #8
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Default Re: Depressing clutch causes voltage drop

Quote:
Originally Posted by madpogue
There is no such switch. If you're certain that it's not the starter interlock switch on the floor, I would second the recommendation that you look for wires being pinched/scraped/whatever by the clutch pedal as you apply it. In any event, if your battery light is on at idle, your alt is probably on its way out anyway (or perhaps your serpentine belt is slipping).

Thanks for quoting my terrible grammar. I'm sure there is a switch, I'm looking at a Haynes Manual for 91-02 S-series saturns and it shows a cruise clutch switch on page 12-19 quadrant B-22. It connects to the Cruise Control Module with a BRN wire and is in series with the stop light switch. This is the first manual shift vehicle I've owned with a CC and I know that I've tried shifting gears with the CC enabled just to see what happens, it disables when the clutch is tapped just the same as if you bumped the brake. Unfortunately the manual doesn't indicate the physical location of the switch or the Cruice Control Module. I'm guessing somewhere under drivers side kick panel, can anybody give me an idea what to look for? If I can find the Cruise Control Module I can probabally follow the wiring to the switch.

Thinking back it's been about a year since I used the CC because it doesn't work quite right, it intermittantly runs the speed up about 15 mph above the set speed then goes into hysterisis and bounces between the set speed and 15mph over. Maybe I should just disconnect the CC altogether and see if that fixxes the problem.
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Old 07-16-2006, 11:13 PM   #9
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Default Re: Depressing clutch causes voltage drop

That Haynes manual is correct for the year of the car they happened to use to write the manual. Their notorious for being wrong for other years/models. The 1996 FSM shows no clutch switch. My eyes, when I crawl up under the dash ('96 SW2 5-speed, factory cruise), show no clutch switch.

Your cruise's overspeed problem is a classic symptom of a failed cruise control module. You could try to find one at a boneyard; they're not hard to R&I. It's doubtful that this is associated with your charging problem, but since it's on the fritz anyway, yeah, pull the cruise fuse and see what happens.
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Old 07-17-2006, 01:49 AM   #10
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Default Re: Depressing clutch causes voltage drop

Quote:
Originally Posted by madpogue
That Haynes manual is correct for the year of the car they happened to use to write the manual. Their notorious for being wrong for other years/models. The 1996 FSM shows no clutch switch. My eyes, when I crawl up under the dash ('96 SW2 5-speed, factory cruise), show no clutch switch.

Your cruise's overspeed problem is a classic symptom of a failed cruise control module. You could try to find one at a boneyard; they're not hard to R&I. It's doubtful that this is associated with your charging problem, but since it's on the fritz anyway, yeah, pull the cruise fuse and see what happens.

Minor derail here:

If there isn't a switch then how does the cruise control know not to rev the engine when the clutch is depressed?

I'll take a flashilght out and look at it tomorrow after work and provide a report of my findings.
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Old 07-17-2006, 06:29 AM   #11
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Default Re: Depressing clutch causes voltage drop

madpogue's right (He usually is.). There is no clutch switch for the cruise control in later model Saturns. I'm not sure what year they got rid of the switch. The PCM controls the cruise control and if it senses the RPMs rising, which they will do if you push in the clutch, without a corresponding increase in speed, it shuts down the cruise control. It's fast enough that there's not a significant rev.
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Old 07-17-2006, 12:11 PM   #12
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Default Re: Depressing clutch causes voltage drop

Quote:
Originally Posted by BarnOwl
It's fast enough that there's not a significant rev.
True, but because the tranny isn't keeping the revs up, it's unnervingly abrupt. You actually hear the throttle pedal slapping back up to the idle position. Too bad they couldn't tie it to the IAC somehow, to soften the blow a little.
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Old 07-17-2006, 12:43 PM   #13
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Default Re: Depressing clutch causes voltage drop

Quote:
Originally Posted by madpogue
True, but because the tranny isn't keeping the revs up, it's unnervingly abrupt. You actually hear the throttle pedal slapping back up to the idle position. Too bad they couldn't tie it to the IAC somehow, to soften the blow a little.
Why would they bother? You aren't supposed to be shoving in the clutch with the cruise control on. The abrupt slap will remind the problem spot in the driver's seat of that fact.
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Old 07-17-2006, 12:54 PM   #14
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Default Re: Depressing clutch causes voltage drop

Quote:
Originally Posted by BarnOwl
Why would they bother? You aren't supposed to be shoving in the clutch with the cruise control on. The abrupt slap will remind the problem spot in the driver's seat of that fact.
You shouldn't have to turn off the cruise just to shift. They shoulda just kept the clutch switch. Yeah, I don't imagine wanting to use the Resume function after shifting, but given the god-awful position of the cruise main on-off switch, it's a pain turning it off and back on again. I just leave the main switch on all the time anyway.

Actually, I *can* think of a time that you'd want to retain the cruise speed memory while shifting. Cruising in fifth at, say, 45 MPH (typical county trunk speed). You want to pull out to pass someone. Downshift to fourth, execute the pass, shift back into fifth, hit "Resume". Only way to do that is to tap the brake pedal to interrupt the cruise, or deal with the "slap" by using the clutch.
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Old 07-17-2006, 10:40 PM   #15
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Default Re: Depressing clutch causes voltage drop

Here is a good question. WHat controls the vehcile speed since there is no cruise motor or cable attatched to the throttle body? I have a92 (as seen in my pic) with intermittent working cruise.
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Old 07-17-2006, 11:55 PM   #16
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Default Re: Depressing clutch causes voltage drop

The cruise control is attached to the gas pedal inside the car.
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Old 07-18-2006, 10:58 PM   #17
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Default Re: Depressing clutch causes voltage drop

Thanks for the heads up on that one man. Appreciate it. I didn't think it was. Now I know.
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Old 07-19-2006, 03:49 AM   #18
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Default Re: Depressing clutch causes voltage drop

I am finding your theory hard to believe. The fact that it only comes on with the clutch depressed, or under less load, the light comes on. That light only comes on when voltage drops below 12V, and no other reason. The fact that the only time that light comes on is then, proves that it deals with the alternator. Whether the belt has no tension on it to turn the alternator enough to maintain 12+V or if the alternator is failing, your problem is there in that circuit. My bet is the tensioner is shot, but test your alternator for free at advance, and physically take a 14mm wrench under your hood and turn your tensioner. It should be fairly firm to move, but move "freely, not jerky". If it doesnt move freely, or isnt firm, it is junk.....
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Old 07-20-2006, 02:34 AM   #19
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Default Re: Depressing clutch causes voltage drop

UPDATE:

Well I tried my best to crawl under the dash and take a look at the wiring and couldn't see or feel anything obvious. Just to throw more ambiguity into the problem I realized that there is a literal rat's nest of wires and questionable crimp type, insulation piercing, splices under the drivers side kick panel where an apparently disabled aftermarket alarm system is living. I'm tempted to rip the thing out but I'm afraid if I do I'll disable the ignition and possibly reactivate the alarm in the process. Does anybody have experiance with aftermarket alarms? Is there a safe way of removing one? I realize the answer to this question may be unsuitable for public forums as it could allow a criminal to disable an alarm system, if this needs to be taken to PM or email I'm okay with that.

Is it really reasonable to think that a high resistance short to ground could cause the light on the dash to come on without blowing a fuse somewhere? I guess an alternator test is free and only takes a few minutes but I really don't expect that to be the problem, or if it is it's only part of the problem.
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