Hi people!
I know this threadtopic has been posted a lot of times, but I can't find any posts that is totally simular to my issue. Ok, here it goes...

I got errorcode P0571, scanned with both pro scanner and my own VAG-scanner.

This is my symptoms when errorcode is active:
1. Glowplug lamp in dashboard is flashing, it even flashes as soon as I turn on the ignition.
2. Brakelights work as normal .
3. The symbol in my dashboard saying that I should step on the brakes before switching gears is working as normal.
4. Cruisecontrol is not working.

This is my symptoms when errorcode is erased and not active:
1. Brakelights are active all the time, even when I don't have my foot on the pedal.
2. The symbol in my dashboard saying that I should step on the brakes before switching gears is NOT working.
3. Cruisecontrol is not working.

This is what I have done to try to eliminate the fault:
1. Replaced the wire going from brakelightswitch to ECU and connection under dashboard, because I measured 1.1 kOhm in the wire. After replacing I measured O.L. in the same wire.
2. Replaced brakelightswitch (but since brakelights acts normal when error is active I think the switch is good)
3. Disconnected each brakelight-module, one at a time while erasing error in between every module. Still I got errorcode.
4. Replaced speedsensor and camshaftsensor, without success (this was due to reading of codes with a generic app).

5. Measured with multimeter the wires from brakelights, all resulted in constant beep and 0,3 ohms. 

 

Sorry for any bad english
 

Which ECU pin number did you follow to the brake switch connector? Wire colour?

I followed this print, so pin 17 and the wire was black/red.

Had you experienced a poor battery immediately prior to these symptoms, bad starting etc?

6 minutes ago, MicMac said:

Had you experienced a poor battery immediately prior to these symptoms, bad starting etc?

No, never. I have been driving with this errorcode since may 22. 

It's the other (white/green) wire you need to check, the one to the engine ECU from pin 1 of the brake switch connector, I think.

If you can confirm your engine code I can tell you which engine ECU pin it goes to. 

6 minutes ago, Breezy_Pete said:

It's the other (white/green) wire you need to check, the one to the engine ECU from pin 1 of the brake switch connector, I think.

If you can confirm your engine code I can tell you which engine ECU pin it goes to. 

Yes of course, we checked that wire as well, but I don't remember where I found the pin for the ECU. It may be wrong. Enginecode CAYC. 

4 minutes ago, Skodaper said:

Yes of course, we checked that wire as well, but I don't remember where I found the pin for the ECU. It may be wrong. Enginecode CAYC. 

Here is the diagram for the ECU that we followed. 

The switch has 2 contacts, it sounds like the new one has the second contact giving a brake on signal, this one may well be a high signal going low on activation for security/safety reasons.

 

It could also be a shorted or open circuit to the ECU or possibly adjustment (if its adjustable) whereby the switch is not changing state.

 

You know the correct signal is going to the body control module as the brake lights are working, I would check that the output to the ECU changes state at the same time as the one to the BCM.

Engine ECU pin number 21 in the info I'm looking at, not sure why the disagreement with your diagram.

3 minutes ago, J.R. said:

The switch has 2 contacts, it sounds like the new one has the second contact giving a brake on signal, this one may well be a high signal going low on activation for security/safety reasons.

 

It could also be a shorted or open circuit to the ECU or possibly adjustment (if its adjustable) whereby the switch is not changing state.

 

You know the correct signal is going to the body control module as the brake lights are working, I would check that the output to the ECU changes state at the same time as the one to the BCM.

I have a switch with 4 pins and it is located on the brake cylinder (lots of dismounting before access :()

I will consider your tips, thank you!

7 minutes ago, Breezy_Pete said:

Engine ECU pin number 21 in the info I'm looking at, not sure why the disagreement with your diagram.

Maybe I have the wrong download, but 21 does ring a bell. Can you screenshot and post in the thread for me to see, please?

You might be reading wrong wiring diagrams.

 

Section 13 CAYC

 

Section 13 / 19

I had a similar issue with a previous car, so take this with a pinch of salt. One of the rear brake light bulbs had shorted in a way that brought the brake lights on permanently. I know you said you’ve replaced the bulbs, but have you tried unplugging the high level brake light? Apparently they can get wet and that would cause a short 

2 hours ago, varooom said:

You might be reading wrong wiring diagrams.

 

Section 13 CAYC

 

Section 13 / 19

This is the same manual that I have, but is it not J623 that is ECU? Not J248, wich is diesel control system?

2 hours ago, PopeyeVRS said:

I had a similar issue with a previous car, so take this with a pinch of salt. One of the rear brake light bulbs had shorted in a way that brought the brake lights on permanently. I know you said you’ve replaced the bulbs, but have you tried unplugging the high level brake light? Apparently they can get wet and that would cause a short 

Hello and thank you for the answer. 

I have tried to unplug each brakemodule, reset code, drove until the code came back. I altso measured connection in every module, all good. 

Just now, Skodaper said:

Hello and thank you for the answer. 

I have tried to unplug each brakemodule, reset code, drove until the code came back. I altso measured connection in every module, all good. 

That said, I have though recieved a light in my dash saying that my 3rd brakelight is out of action. This only happens sometimes, although ohms-measured all good

29 minutes ago, Skodaper said:

This is the same manual that I have, but is it not J623 that is ECU? Not J248, wich is diesel control system?

You first posted diagram 1/27

Then 6/15 (1.4 ltr)

 

Looking for CAYC takes us to section 13 which you must follow as this overides the other sections as far as I know.

 

 

Just checking also that you have the same file source also...

S0057380020-Basic_equipment_-_OCTAVIA_II__(L0L)__As_of__May_2011.pdf

Edited 19 September, 20223 yr by varooom

10 hours ago, Skodaper said:

That said, I have though received a light in my dash saying that my 3rd brakelight is out of action. This only happens sometimes, although ohms-measured all good

 That is typical of poor connections. It brings up a fault code but when you check it out it reads ok.

You should look for for corroded or loose connections in all the wiring for the high level brake light - for example in the rubber trunking to the hatch and any connectors behind the trim rear side panels of the car. If that fails, then take off the rear brake light and check for poor solder joints in the unit.

1 hour ago, pikpilot said:

 That is typical of poor connections. It brings up a fault code but when you check it out it reads ok.

You should look for for corroded or loose connections in all the wiring for the high level brake light - for example in the rubber trunking to the hatch and any connectors behind the trim rear side panels of the car. If that fails, then take off the rear brake light and check for poor solder joints in the unit.

I will try to break it down completely. By checking for poor joints in the unit, do you mean the LED-points? Thanks for the tip!

11 hours ago, varooom said:

You first posted diagram 1/27

Then 6/15 (1.4 ltr)

 

Looking for CAYC takes us to section 13 which you must follow as this overides the other sections as far as I know.

 

 

Just checking also that you have the same file source also...

S0057380020-Basic_equipment_-_OCTAVIA_II__(L0L)__As_of__May_2011.pdf

Yes I did, I found out later. Thank you. 

5 hours ago, Skodaper said:

do you mean the LED-points?

Yes, I mean the third, high, LED brake light assembly.

6 minutes ago, pikpilot said:

Yes, I mean the third, high, LED brake light assembly.

Understood. I will look into it. Thank you. 

This problem may be caused by corrosion of connections, I think. I may have read about this somewhere on this forum, but not 100% sure

 

This page shows the brake switch as item 10, described as a 'repair kit'. brake fluid - Octavia(OCT) [EUROPA 2012 year] (7zap.com)

 

If you poke that part number into oemwolf.com, it shows as superseded to 5G0698459, which on this page helpfully has a list of kit contents.,VAG 5G0698459 repair set for brakelight sensor Audi, Seat, Škoda, Volkswagen genuine OEM part kit (oemwolf.com)

 

Note there is a four-pin connector included.

 

Is there any sign of corrosion on the pins of the original switch, if you still have it?

6 minutes ago, Breezy_Pete said:

This problem may be caused by corrosion of connections, I think. I may have read about this somewhere on this forum, but not 100% sure

 

This page shows the brake switch as item 10, described as a 'repair kit'. brake fluid - Octavia(OCT) [EUROPA 2012 year] (7zap.com)

 

If you poke that part number into oemwolf.com, it shows as superseded to 5G0698459, which on this page helpfully has a list of kit contents.,VAG 5G0698459 repair set for brakelight sensor Audi, Seat, Škoda, Volkswagen genuine OEM part kit (oemwolf.com)

 

Note there is a four-pin connector included.

 

Is there any sign of corrosion on the pins of the original switch, if you still have it?

The brakeswitch and connection is in good condition, this was checked by VW garage this summer. They could not find any issue that could cause the error and wanted me to schedule a new appointment, but this was calculated to be 650£, so I passed 😛