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Author Topic: Cruise Control / block 066 Stumper - Clutch Switch Reversed? (x-post from QW)  (Read 6621 times)
trichard3000
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I'm trying to chase down the absence of cruise control in the new ride. Starting with the switch test in VCDS, I used measuring block 066 to check all the switches as per this write-up:

http://wiki.ross-tech.com/wiki/index.php/Checking_Cruise_Control_using_Measuring_Values

Everything passed except for something odd with the clutch switch. According to the write-up, the clutch switch bit should be 0 when, "clutch not depressed" and 1 when, "clutch depressed."

My clutch switch shows the opposite. The switch is changing when I push the pedal but it reads 1 with the pedal up and 0 with it pushed in.

The switch was replaced earlier by the PO for another issue but it turned out the switch was unrelated. The stalk switches all register fine and the brake switches both set the right bits. I'm not throwing any codes for implausible signals from any of the switches. Otherwise the car seems to be running fine.

It's a MY2001.5 6MT car.  At one point it was running phila_dot's map switching bin from this thread:  http://nefariousmotorsports.com/forum/index.php?topic=2872.0title=  It's currently running a jfonz stage 3 base tune. 


Three possibilities:
- The switch is working properly and the documentation is reversed
- The switch is reversed and nothing else is affected.
- Something in the tune is messing with or ignoring this bit.

Does this seem like the clutch switch could be the culprit or is this a red hearing?

Otherwise, does anyone have any ideas what to look at next?

*Thanks*
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ddillenger
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There are two different clutch switches. One normally open, one normally closed. Check the part number on the installed switch. I bet it's incorrect for your model.
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trichard3000
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There are two different clutch switches. One normally open, one normally closed. Check the part number on the installed switch. I bet it's incorrect for your model.

This is definitely plausible.  It looks like this being wrong would have other effects though, or is that only on older models?
 
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elRey
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When during pedal travel does the switch trip? When you barely press the pedal, or close to the end of the pedal travel (close to the floor)?
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trichard3000
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When during pedal travel does the switch trip? When you barely press the pedal, or close to the end of the pedal travel (close to the floor)?

The current switch trips when I barely press the pedal. 

Regardless, I think that the reversed switch is confirmed.  I pulled the connector and jumpered the connection to flip the bit.  The cruise control now works as expected.  Strangely, nothing else seems to be affected by this.

Infinkc is the PO and he still has the original switch which turned out to be fine.  He's sending it my way to confirm the final fix.

Thanks for helping confirm that a reversed switch is even possible.
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nyet
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Glad you got to the bottom of it!

Need to file this away in my head for the next time i get to a car with non functioning cc.
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nyet
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The current switch trips when I barely press the pedal. 

This actually makes sense if you think about it.

The starter switch is there to prevent you from starting the motor unless the clutch is all the way down.

The intent of the other switch is to disengage the cruise control if the clutch moves at all..
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ME7.1 tuning guide
ECUx Plot
ME7Sum checksum
Trim heatmap tool

Please do not ask me for tunes. I'm here to help people make their own.

Do not PM me technical questions! Please, ask all questions on the forums! Doing so will ensure the next person with the same issue gets the opportunity to learn from your ex
trichard3000
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It's hard to tell without doing more research, but it looks like at some point this switch had other uses.

From this thread:  http://forums.audiworld.com/showthread.php?mode=hybrid&t=1512421

Quote
per the Bentley manual, the function of the Clutch Pedal Position switch (aka Clutch Vacuum Vent Valve Switch):

This signal is used to avoid RPM over-oscillation and load change impacts when changing gears and is also used for the cruise control system.

I haven't noticed any differences with it just being jumpered to look like the clutch is always engaged.  I haven't driven very much yet, though.  If it acts very differently I'll report back.

Thanks again!
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