Why is there a switch on the clutch, similar to the one on the brake pedal?

I guess its because the ECU needs to know when the clutch is being pressed, but why does it need to know?

Could a faulty switch, one that tells the ECU the clutch is contantly being pressed, cause a drop in BHP?

It has 2 uses, first to hold revs when changing gear (only for about a second) to enable smoother gear changes, and second to deactivate cruise control when clutch is touched (on those with cc).

Could it effect BHP if the switch was faulty?

Shadeyman said:

Could it effect BHP if the switch was faulty?

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Not quite sure to be honest.

Shadeyman said:

Could it effect BHP if the switch was faulty?

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Definitely - no.

Any chance someone could provide a bit more detail as to where to locate this clutch switch?? Mine may me faulty as the rev's drop immediately when the clutch pressed.

About once in a blue moon the rev's will remain high for about a second when pressing the clutch in my car.

A pic would be super for other users on here

Top of the clutch pedal, similar position to the brake pedal switch.

Item 3 in this diagram.
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If anyone knows the answer to this question please enlighten me as I am on a serious quest to determine the solution to a serious problem with my car :yuck:

Could a faulty clutch switch have any effects on the behavior of the ECU and its fuel management system? My query specified further, could a faulty clutch switch interfere with the ECU and manipulate a cut out of fuel in to the engine? Or can it in any way possible simply interfere with the ECU system whatsoever??

Never did find out for sure if it can effect BHP(eg. if the ECU thinks the clutch is pressed will it hold the engine back when the throttle is pressed). Lets hope you have more success.

You could test drive it with the switch disconnected to find out. Worst thing that could happen is that it registers a clutch pedal switch fault.

Shadeyman said:

Never did find out for sure if it can effect BHP(eg. if the ECU thinks the clutch is pressed will it hold the engine back when the throttle is pressed). Lets hope you have more success.

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Yes that is true, no definite answer was really stated on the thread, I did keep an eye on it for a while but nothing came through

I also did carry out a wide search on Bosch ECU`s and general ECU operations and programming following your Dodgy Geezer thread but I had no luck what so ever again , both in the forum and the internet, the subject on the thread got me going after recent events, I am still hunting and I will find something, never give in, stubborn determination which only rests when I fall asleep.....

Davren said:

You could test drive it with the switch disconnected to find out. Worst thing that could happen is that it registers a clutch pedal switch fault.

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Thanks for the info, I will definitely give it a try and see if my Ahhhh kangarooing JTD calms back down to normality

I just diconnected the switch as Davren suggested and drove about 2 miles on a local dual carriageway. No errors reported via the dash and it did seem a little quicker but couldn't be 100% sure. Could this mean I have a faulty clutch switch?

I started the Dodgey Geezer thread because I've been looking to buy a summer project car and I was suspicious of a car I went to see. The price was low and the problems easy to fix, I thought maybe he had unplugged a few sensors to cover a more serious fault.

Shadeyman said:

Could this mean I have a faulty clutch switch?

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Not neccessarily, I think it's main function is to disengage Cruise Control but as it's also fitted to Stilos without CC, I suspect it has a minor influence on engine performance. Possibly just improved driveability when changing gear.

Shadeyman said:

I just diconnected the switch as Davren suggested and drove about 2 miles on a local dual carriageway. No errors reported via the dash and it did seem a little quicker but couldn't be 100% sure. Could this mean I have a faulty clutch switch?

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Another mystery Shadeyman.......

You are running your ECU scan through an ELM 327 v1.3b cable right? So you are getting a near on full feed of the ECU diagnostics right? So no error codes appeared and it seemed to run better... to be honest I will may look in to replacing the part and seeing how it goes from there.

Just a quick question, did your query regarding the clutch switch derive from unusual throttle response??

This is all I could find from Google.

"Used by the ECU, to tell when the clutch is engaged, injected fuel quantity is then reduced briefly to alleviate engine shudder when changing gear. Also used as a signal to deactivate cruise control if currently active".

Davren said:

This is all I could find from Google.

"Used by the ECU, to tell when the clutch is engaged, injected fuel quantity is then reduced briefly to alleviate engine shudder when changing gear. Also used as a signal to deactivate cruise control if currently active".

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That is brilliant, hells knows what I was googling wrong, thank you very much Dave you have not only given this thread an answer but you may have also just solved my kangaroo mystery, I will keep you posted

Ballackcanavaro99 said:

Just a quick question, did your query regarding the clutch switch derive from unusual throttle response??

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No, not really as I cant say I've noticed any lack of power. The reason I asked was because I tend to wear boots a lot of the time and due to the fact I'm a size 11 and theres not much room down there so my foot is usually resting on the clutch. Sometimes the clutch is being pressed and due to wearing boots I dont notice.

So I wondered if my big feet were having any unwanted effects on performance as I dont have cruise controls and the switch is fitted to my car suggesting the switch does more than just cancel the cruise.

However, our old Stilo would sometimes judder when the clutch was pressed.

Davren said:

This is all I could find from Google.

"Used by the ECU, to tell when the clutch is engaged, injected fuel quantity is then reduced briefly to alleviate engine shudder when changing gear. Also used as a signal to deactivate cruise control if currently active".

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Funny enough Ive started to get the odd judder when changing gear recently. Could be me though. When CC is on and I hit clutch revs rise before they fall. Does this happen with others who have CC. Its just with the brake as soon as that's tapped CC is disenguaged instantly.

Most Easterly Pandas said:

Funny enough Ive started to get the odd judder when changing gear recently. Could be me though. When CC is on and I hit clutch revs rise before they fall. Does this happen with others who have CC. Its just with the brake as soon as that's tapped CC is disenguaged instantly.

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I'd kinda expect revs to rise in those circumstances, (a) because you're suddenly cutting the load on the engine, so it will initnially rev and (2) it's probably programmed to do that to avoid emmissions.