2010 Ibiza TDi 1.4 Brake lights stuck, where's the sensor/switch?

[martin0642]

Hi all - I'm hoping one you fine folk can help me with this puzzle.....

My coil warning light started flashing recently, just after I had to slam on on a motorway. I got home; switched off and on again and everything seemed fine. Checked the bulbs/fuses/brake lights and they all seemed fine - no loss of power, no weird braking issues, just a flashing light that stopped after the engine was switched off.

It has now come back on again and the brake lights are stuck on (regardless of whether main lights are on or not). I've scoured the internet looking for solutions and found many threads talking about the brake light swicth at the top of the pedal - but after looking at mine.....there isn't a switch on the pedal. The only electrical cable I can see going to any of the pedals is the one to the throttle. (see attached picture).

I found one thread where someone mentioned briefly that they were told be SEAT that their car doesn't have a switch on the pedal, it has a sensor on the master brake cylinder. So....is that likely to be the same for mine? (Their car was older and not an Ibiza)

If so - where do I find the damn thing? (It would be so helpful to have a Haynes manual for these cars....urgh...anyway...)

Any advice folks?

I should add that I have *very* little money to throw at the car right now so if this is something I can fix I will; I'm reasonably handy with such things (but know my limits!).

Also - the car is running fine besides this issue - although it did have a weird problem with the front wheel seeming to be stuck after being left for a couple of days; like I was trying to reverse over something when backing out of our car park space. Took it in to get it checked and was told all was well. Hasn't happened for quite a while now.

Any help would be much appreciated.


Oh...I can't post images .... ok well it was an image of the brake pedal with no wires coming out of it in any direction.

 

[RUM4MO]

I think that you are correct in that the brake light switch has moved out onto the master cylinder, so might be tricky to find if it is behind the servo - bother bother!

Wheel sticking after not being used for a few days, I'd think that it will have been rusting of the pad(s) to the disc(s) - normally this is more a rear brake issue. Did you wash the car before leaving it for a few days?

Edit:- I've just ordered up a Haynes book, really for my wife's 6C Polo, but as that Haynes books mainly just covers 6R Polo, I'm also hoping it will be useful for some things on my daughter's late 2009 Ibiza 1.4 SC - that book should arrive tomorrow or so, so I might be able to point you towards the brake light switch - just one thing, as you might have worked out, I'm guessing any problems with these later brake light switches will cost quite a bit more than the previous unreliable ones that were on the brake pedal!!

 

[TopBanana]

This should help show you where its located, number 9 on the diagram.
http://www.catcar.info/audivw/?lang...sZHRhZmVsPT02MTExMHx8R3JhZmlrPT0wNjExMTA2ODk=

 

[RUM4MO]

"Repair kit" - that's handy!
I'll need to have a look at daughter's late 2009 Ibiza after I've finished checking it again for "excessive current draw" next week! Also on wife's August 2015 Polo. (good to be prepared for these sorts of things)

 

[martin0642]

I think that you are correct in that the brake light switch has moved out onto the master cylinder, so might be tricky to find if it is behind the servo - bother bother!

Wheel sticking after not being used for a few days, I'd think that it will have been rusting of the pad(s) to the disc(s) - normally this is more a rear brake issue. Did you wash the car before leaving it for a few days?

Edit:- I've just ordered up a Haynes book, really for my wife's 6C Polo, but as that Haynes books mainly just covers 6R Polo, I'm also hoping it will be useful for some things on my daughter's late 2009 Ibiza 1.4 SC - that book should arrive tomorrow or so, so I might be able to point you towards the brake light switch - just one thing, as you might have worked out, I'm guessing any problems with these later brake light switches will cost quite a bit more than the previous unreliable ones that were on the brake pedal!!

Thank you for the reply - and yes I gathered this will cost quite a bit more. If nothing else - I could have fixed a switch located on the pedal myself. But after a quick look at the engine earlier I doubt I have the resources to get to the right point on the master cylinder.

Bother indeed....

However - I would be very grateful if you find any more info you can pass on

 

[martin0642]

This should help show you where its located, number 9 on the diagram.

Thank you! That's very helpful indeed. Now I just need to find a way to get at the damn thing.

 

[RUM4MO]

It looks very do-able if you don't mind struggling for access!

It is located on the underside of the master cylinder, so out in front of the servo. Securing bolt is Torx caphead, tightening torque is 5NM so very little.

"remove connector, usual VAG type with locking tang, remove bolt, withdraw switch, fit new switch, fit bolt and torque to 5NM, fit connector - job done!

You will be able to see it easily using a small mirror and light, or special mirror with light - which I seem to have!

Edit:- I'd reckon that the first thing you need to do is to unplug that connector and see if the brake lights go out, before moving forward with this repair.

 

[martin0642]

It looks very do-able if you don't mind struggling for access!

It is located on the underside of the master cylinder, so out in front of the servo. Securing bolt is Torx caphead, tightening torque is 5NM so very little.

"remove connector, usual VAG type with locking tang, remove bolt, withdraw switch, fit new switch, fit bolt and torque to 5NM, fit connector - job done!

You will be able to see it easily using a small mirror and light, or special mirror with light - which I seem to have!

Edit:- I'd reckon that the first thing you need to do is to unplug that connector and see if the brake lights go out, before moving forward with this repair.

Thank you so much for this! I had a look at it this morning, before reading this - and that makes more sense now. The diagram linked above seemed to imply the sensor was off to the left side as you looked at it...which it isn't. I can see an electrical connector to the underside though...damn fiddly to get to but I *think* I may be able to get to it. At least now I have something to work off.
?
There's also a sensor to the top of the fluid reservoir but I'm assuming that's for something different...ie brake system rather than lighting.

I had some advice on another forum to simply disconnect the battery for 10 mins+ to reset everything and see if that cleared it. In fact that's why I was under the hood earlier...however I decided against it! It's been a very long while since i've had to do anything more serious than standard maintenance on a car and the complexity of recent engines is...yeah. Having read around I realised I may possibly cause myself more problems trying to reset everything and get it all running properly again if I disconnect the battery.

(Seriously though... even a battery change involves complex electronics and the ecu...really? Urgh)

Anyway - as soon as I get the chance i'll have a proper look at the cylinder and see if I can at least get to the sensor and disconnect as you advised and see what happens then.

Thank you again - i'll report back whatever happens in case someone else has the same issue.

 

[RUM4MO]

Taking the earth lead off the battery should not cause you any problems, only the electric window top/bottom limits need resetting also the fuel computer will lose its data and the clock will need reset.

The sensor in the brake fluid reservoir is for fluid level only.

 

[martin0642]

Taking the earth lead off the battery should not cause you any problems, only the electric window top/bottom limits need resetting also the fuel computer will lose its data and the clock will need reset.

The sensor in the brake fluid reservoir is for fluid level only.

Once again - thank you! I'm getting a bunch of odd advice in other places but yours sounds much more sensible and achievable. I'm going to have a look at it now - I doubt I'll try pulling the battery though..whilst it may not add to my problems I struggle to see how it's going to fix anything besides possibly removing fault codes.

 

[martin0642]

I'm heading out to the car now but thought i'd add...whilst I was here - that I found a workshop manual online - I don't think I can post links (link seems legit though) but it's workshop-manuals.com - found the page for stripping down the cylinder and a specific section for the brake sensor.

Fingers crossed!

 

[RUM4MO]

This is all a bit disappointing as the previous brake light switches were very problematic and got revised quite a few times - and now this "better" way of doing it is still capable of causing problems, I'm guessing that this time the switch is a "hall sensor" and it senses the master cylinder piston moving, could be wrong though.

 

[martin0642]

This is all a bit disappointing as the previous brake light switches were very problematic and got revised quite a few times - and now this "better" way of doing it is still capable of causing problems, I'm guessing that this time the switch is a "hall sensor" and it senses the master cylinder piston moving, could be wrong though.

Yeah I agree...although given how often the previous switches seemed to break I can kind of understand why they opted for an alternative - and I find many less threads about MK5s having this issue.

So I've just disconnected the sensor - fiddly as all hell but doable even with my large hands. As you suggested I just disconnected it and then had a look at the brake lights - still on. I was wondering when you suggested that though - would that not produce the same issue anyway as presumably the brake lights being stuck on shows a fault with the sensor, so a disconnected sensor would in fact produce the same result as a broken one.

I haven't done anything else yet - managed to grab a photo of the sensor to check the part number though (amazing what you can do with mole grips and a smartphone)

 

[RUM4MO]

I wonder if you disconnected the sensor from its wiring and it still kept the lights on?

If it did, maybe that is good as it might indicate that this circuit has been design to fail safe, mainly the older versions failed unsafe and you ended up with no brake lights, I had that once with the earlier switch and due to having read about it, used great caution when braking on the way back home, did not use the car until I got a new switch next day, that next one eventually failed the same way about 8 years later!

I'd guess, with that sensor it needed a metal or magnetic pellet to be inline with the sensor active area, so removing the complete sensor from the cylinder with the lead still connected would replicate the brake pedal being pressed,maybe? Or the other way round?

I'm in the middle of chasing a "draining battery" issue with my late 2009 Ibiza, or I could have disconnected the sensor on that car and see how it behaves - sorry.

 

[martin0642]

I wonder if you disconnected the sensor from its wiring and it still kept the lights on?

If it did, maybe that is good as it might indicate that this circuit has been design to fail safe, mainly the older versions failed unsafe and you ended up with no brake lights, I had that once with the earlier switch and due to having read about it, used great caution when braking on the way back home, did not use the car until I got a new switch next day, that next one eventually failed the same way about 8 years later!

I'd guess, with that sensor it needed a metal or magnetic pellet to be inline with the sensor active area, so removing the complete sensor from the cylinder with the lead still connected would replicate the brake pedal being pressed,maybe? Or the other way round?

I'm in the middle of chasing a "draining battery" issue with my late 2009 Ibiza, or I could have disconnected the sensor on that car and see how it behaves - sorry.

I tried replying to this last night but for some reason it wouldn't work.. (my laptops are all suffering tech issues as well - one of those months!)

Anyway - no need to apologise, you've been more than helpful! I've just dropped it off at the garage to get a proper diagnosis done though. I have no doubt I can fix the switch, it's fiddly but doable. However - given that I have no way of testing whether it actually is the switch and the apparent possibility of something else in the system being wrong (electrical..which is mostly beyond me...other sensors etc etc) I'm playing it safe. If the garage says its the switch I'll do teh work myself. If it's something else it may have to stay with them...thank god they're good!

I'll report back so anyone else having the same issue can at least get some pointers. Finding the workshop manual online was invaluable! As has been the advice - thank you

 

[martin0642]

Update: It is indeed the brake switch apparently. Sadly...the garage went ahead and ordered it, having already got one from another supplier which turned out to be the wrong part (the same place I would have gone incidentally).

I asked them to just diagnose but since they have the part on order i'm going to let them go ahead and do it - £124 all in. COuld be worse! At least they can clear the code and check that's all it is.

And now i'm going to find myself a decent OBD reader for future use. Anyone try the bluetooth ones you can get? They seem to get good reviews and given the fact i'll use it rarely (I hope) seems a worthwhile investment.

 

[RUM4MO]

Oh well, by the time they had fully diagnosed it I suppose it would not cost much more to actually fit the new one - and if they had mis-diagnosed that fault you would have been a bit annoyed if then you bought and fitted a new switch. I've never tried going to a garage for just a diagnosis!

OBD2/OBDE scan tools, yes there are lots about, as I have been a VW/Audi/SEAT owner/looker after since May 2000, I bought VAG-COM and now updated to VCDS and no doubt will update to VCDS HEXNET when I need to, but that sounds a bit like overkill for what you are wanting - though it does cover the complete suite of smart modules in all VW Group cars. Like in your case, this failure might not have been clearly defined as most scan tools only cover engine module detected faults.

Aim to get one that is fully compliant for VW Group cars and includes all their smart modules.

Carista does seem to do that with some "personalisation" functions included, I bought that to replace an old Gendan self contained scan tool to carry in the car. The Carista dongle, while expensive operates in lo powered version of Bluetooth for IOS devices which leaves the WiFi free for other things, like sending collected data to a printer.

There are cheaper OBD2 dongles with only Bluetooth for Android users though which can run with Carista.

Edit:- Carista is quite trustworthy as it did identify an issue with my wife's August 2015 VW Polo - which did turn out to be a suspect media system On/Off switch!

 

[martin0642]

Oh well, by the time they had fully diagnosed it I suppose it would not cost much more to actually fit the new one - and if they had mis-diagnosed that fault you would have been a bit annoyed if then you bought and fitted a new switch. I've never tried going to a garage for just a diagnosis!

OBD2/OBDE scan tools, yes there are lots about, as I have been a VW/Audi/SEAT owner/looker after since May 2000, I bought VAG-COM and now updated to VCDS and no doubt will update to VCDS HEXNET when I need to, but that sounds a bit like overkill for what you are wanting - though it does cover the complete suite of smart modules in all VW Group cars. Like in your case, this failure might not have been clearly defined as most scan tools only cover engine module detected faults.

Aim to get one that is fully compliant for VW Group cars and includes all their smart modules.

Carista does seem to do that with some "personalisation" functions included, I bought that to replace an old Gendan self contained scan tool to carry in the car. The Carista dongle, while expensive operates in lo powered version of Bluetooth for IOS devices which leaves the WiFi free for other things, like sending collected data to a printer.

There are cheaper OBD2 dongles with only Bluetooth for Android users though which can run with Carista.

Edit:- Carista is quite trustworthy as it did identify an issue with my wife's August 2015 VW Polo - which did turn out to be a suspect media system On/Off switch!

Once again - awesome reply

Yeah I hesitated to take it to the garage for diagnosis but given the range of possibilities I figured it would be better to be safe than sorry. My car is vital for my job (i'm self employed) so rather than spend £20 on a part only to find that wasn't the issue I decided to take a gamble ....which annoyingly turns out to be costing me £100 more. However - £100 for peace of mind? In this case I think it's worth it. Well that's what i'm telling myself anyway. I'm slightly annoyed they ordered the part to be honest - if they hadn't I would have done it myself. But..they did and they are generally pretty great when it comes to sorting my car so I won't complain.

Thank you for the heads up about Carista - i was looking through the bewildering array of reveiws for those types of module so getting some feedback is great. That's a perfectly reasonable price too...£30 ish ...for what I need it's worth it and VCDS would probably be overkill.

When everything is sorted next week i'll confirm that nothing else came up and if anyone ese reads this thread with the same issue I can point them at the online manuals and parts needed.

 

[Inzombie]

Hi, i have same problem, scanning with VCDS and this is the result
1 Fault Found:
16955 - Brake Switch (F)
P0571 - 008 - Implausible Signal

I look at top of the pedal and never found a switch or something like that.
Right now i remove this part and the part number is 1K0 945 459
I`ll order at eBay for 20 bucks

Saludos desde México!

 

[RUM4MO]

Good luck with that repair, but, if you looked at the link to the parts listing given in an earlier posting, I'm guessing that the part you have ordered is only one part of that switch assembly, now you might be luck and that is the part that is faulty, but the parts list only lists a complete "repair kit" and with VW group's very poor/bad record on selling cars with badly designed brake light switches, I'd be guessing that they are taking no chances and have revised that switch and so find that it is better to supply a complete repair kit. What you will be buying on ebay will be superseded parts that have been disposed of by VW group parts stores around the world.