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BMW 3-Series (E90 E92) Forum > E90 / E92 / E93 3-series Technical Forums > Mechanical Maintenance: Break-in / Oil & Fluids / Servicing / Warranty > E9X Clutch stop/start sensor bypass



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      11-07-2007, 04:38 PM   #1
O-cha
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E9X Clutch stop/start sensor bypass

Started working on this today and made some progress.

Clutch sensor:

It's under the lower dash, you have to take the three hex screws off and pull down and out to remove it. There's a bunch of stuff connected to it, its easier to remove all the connectors and put the lower dash in your backseat.

Following up the clutch pedal at the top there is a cylinder which takes your pushing of the clutch pedal and turns it into pressure. On the LEFT side you will find a set of wires running into a little piece that looks like this, the connector is missing. (see below to see what it looks like)




It's easy to pop off, so much so that I cant believe it hasn't on its own. This is the sensor that tells the car if you have the clutch in a little, for the cruise control, or all the way, so you can start it.

To make it so you don't need to depress the clutch to start the car you need to jump these two wires. This wont affect your cruise control since it is a separate wire.



Car starts without the clutch depressed now. I am not responsible for any damage you do by following these instructions, attempt at your own risk.

This is as far as I have gone today, but for a sneak peak, this is the already in place and threaded bolt that can be used to create a clutch stop. It's already technically the clutch stop, just not long enough.





I'll need to find out what size thread this is and then fabricate something for it. If anyone has some ideas throw them out.
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      11-07-2007, 04:43 PM   #2
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Oh yea, comfort access people, you wont be able to get only ignition power with the keys in your pocket, the car will just plain start. I believe if you take the FOB out and insert it into the dash you will be able to get ignition only power if you so desire, though I'm not sure why you would.



Update: OK just bypassing it this was isn't going to work for comfort access people, not sure about normal people. It's hard to turn the car off without restarting it, and the car throws an error after driving a bit because the longer sensor is tripped while the shorter one is not.

Solution: A relay switch, I'll pick one up tomorrow from radio shack. Going to wire it to when the cruise control sensor trips (you barely have to depress the clutch) a circuit will complete between the 12v line and the 12v fully depressed line. Unfortunately simply jumping the cruise control line to the fully depressed line does not work because for some reason the cruise control line is only 8v as opposed to 12v for the fully depressed line. But 8v will be sufficient to activate the relay and pump 12v into the fully depressed line.

I believe the threaded rod on the firewall is 1/4-28, which stands for 1/4 inch diameter 28 threads per inch. I tried 1/4-20 which is the alternate version and it threaded 2 times before stopping, which is indicative of the wrong thread density.

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      11-09-2007, 11:04 PM   #3
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If anyone actually cares about this let me know. I gave up for various reasons but I have a quite a bit more info and such if anyone wants to take up where I left off
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      01-02-2010, 05:15 PM   #4
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Thanks for the write-up. As a follow-up, have you left this mod on or have you reverted back to the original setup. Any adverse effects?
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      01-03-2010, 09:02 AM   #5
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I'm not sure what benefit this mod provides. You will not be able to put the car in "accessory" mode because the engine will start every time. The accessory ignition mode is necessary for several maintenance functions such as resetting service indicators and fault code reading with either a BT scanner or OBDII scanner.
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      01-03-2010, 03:34 PM   #6
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Quote:
Originally Posted by KINetics View Post
Thanks for the write-up. As a follow-up, have you left this mod on or have you reverted back to the original setup. Any adverse effects?
Glad this was helpful to you but see below.

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Originally Posted by ENINTY View Post
I'm not sure what benefit this mod provides. You will not be able to put the car in "accessory" mode because the engine will start every time. The accessory ignition mode is necessary for several maintenance functions such as resetting service indicators and fault code reading with either a BT scanner or OBDII scanner.
The mod is not jumping the wire, it's for a clutch stop and hat was one problem I came across with comfort access cars.

The bigger problem though is that the car has an engine protecting feature directly linked with the clutch position sensor.

Simply jumping the sensor eliminates this and make it possible to blow a connecting rod out of your block. It's not a 100% necessary feature, but it's nice to have.




The only way to do this properly is instead of jumping that 12v wire run it through a momentary contact switch mounted in such a way that when the clutch bottoms on the stop it switches.

It's doable and I could make a plug and play for it but no one really wants it.
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      02-20-2010, 04:02 PM   #7
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Mine came loose somehow, and this thread saved me!!!! Thank you! And thanks for the internet.
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      04-23-2010, 06:51 PM   #8
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Mine came loose somehow, and this thread saved me!!!! Thank you! And thanks for the internet.
Same here. I installed the M dead pedal and the sensor popped off during my struggling. Thanks so much
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      02-25-2011, 12:51 PM   #9
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What about the possibility of jumpering both the 12v-8v cruise control and 12v-12v push start, but wiring small switches for both in case you wanted to still use cruise control or the "On" function. Would that still throw a code do you think? What type of resistor would I need to drop the current from 12 to 8 volts? I like the idea of just hoping in and pressing the start button (no need to press the clutch in)...
Thanks,
Chris

Last edited by listed5; 03-02-2011 at 04:01 AM.
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