Clutch pedal switch problem

[taximeistergolf]

Recently replaced the brake light switch, but immediately on trying to start up, the vagcom tells me the clutch pedal switch is faulty. I have now replaced this, (twice incase the first one was faulty). Vagcom still cannot cancel fault. My coil light is now flashing intermitantly, and the car can now be started without the need to press the clutch. Also it only fires up after about 4 seconds. Is this familiar to anyone?

[a8 tech]

Yes,post vag com log and also a picture of the previous clutch switch so I can see if you fitted it correctly as this is often the cause installation

Installing
Pull out operating rod -arrow- all the way before installing clutch pedal switch.

When installing clutch pedal switch for engine start, press clutch pedal -1- all the way down . Hold clutch pedal in this position.
Guide clutch pedal switch for engine start-2- through opening in retainer, and at the same time push operating rod against clutch pedal and secure switch by turning it 45° in the direction indicated

[taximeistergolf]

Thanks for your prompt reply. Unfortunately I dont know what Vagcom said (my mechanic did this for me ), however I can remember that every time he tried to clear the fault, it kept returning immediately with the same fault. I fitted the clutch pedal switch myself, but nievely didnt fit it as per your instructions. I didnt touch the centre rod (plunger), and I didnt keep the clutch pedal pushed in whilst fitting!
It has today gone to local Audi dealers, and they have replaced the switch again, but it still hasnt worked. Surely they will have fitted it as per your instructions? They have also changed another switch which is operated by the clutch pedal (higher up?) which still hasnt cured the problem. They are now talking another 3 hours labour to trace it back to control units/relays/ broken wiring, etc. behind the dashboard. Hope this helps. Thanks Graham

[a8 tech]

Next step is to check the multi block connection in the passenger side E box, this floods with water and causes corrosion of the terminals which in turn causes a resistive circuit and hence the fault but it is not uncommon for technicians to fit the switch incorrectly so as the switch runs direct to the engine ecu and auto box (if fitted) then its unlikely to be the control units and far more probable to be the suggested areas.

I have removed the attachments before the mods see them

Regards A8

[taximeistergolf]

It sounds like its a job for the Audi Techs to sort out. Thanks for helping

[taximeistergolf]

Been doing some major thinking overnight! Do you know that if the switch is merely fitted(ie twisted and locked) without the clutch pedal being pressed fully in that this will render the switch inoperative? I can recall vaguely that after fitting it (incorrectly), that the first time I pressed in the clutch pedal there was a small click, and I wonder if this was the plunger breaking inside because of my incorrect fitting. Sorry to be a pain, but I envisage the car coming back from Audi with a v. hefty repair bill caused by a very simple fitting error!

[taximeistergolf]

Can't believe the way this is going. Have been in to local dealership, whom I must say have been very helpful. They even took me into the workshop to speak to the technician. Clutch pedal switch has been fitted correctly, he even showed me the fitting diagrams which you posted for me to look at. Block connectors have been checked, and are ok, and he is going through what looks like a maize of wiring trying to isolate what may be a broken wire. Best case scenario, I am looking at £400. Worst case scenario is that the ECU may have to be changed to eliminate the problem at a cost of £600, making a £1000 in total! Any advice? Thanks Graham

[a8 tech]

I would ask them to confirm if the switch status changes when bypassed or bridged as this will eliminate the ecu and the wiring, as I have mentioned these switches can be a nightmare with only one go at fitting them for the correct position to be assumed.If the fault clears after bypassing the circuit then it must be the switch as the circuit is simple.
If the switch is in the open position the engine will not crank, if the switch is in the closed position it will crank.If the switch sends the signal as if the pedal is pressed but its not then the engine will crank without you pressing the pedal so if you then disconnect the switch the engine will not crank as the circuit is open but if you bridge the connector the engine will crank.
So the last bit eliminates the ecu and the wiring and indicates a contact problem within the switch although new it appears its not working,bizarre but very possible

[taximeistergolf]

Thanks once again for your comprehensive reply. I am going in again tomorrow morning, and I will try and find out if this operation has been carried out. I will let you know what happens next. Kind regs Graham

[taximeistergolf]

Audi cannot resolve this problem despite car being in for 3 days. Coil light still flashing and clutch pedal switch has failed despite them fitting 3 new ones (as per proper procedure).
Problems only began immediately after fitting new brake pedal switch, and although not showing as faulty, wonder if this is directly related to the problem. Going to fit a new brake and clutch pedal switch at the same time to see if this resolves the issue