Third brake light not working but no error light or error code in VCDS

[mirceaculita]

Hello,

As the title says,

My third brake light stopped working. I have no lights on the dash and no errors with VCDS in central electronics. I tried the output test for brake lights and they do not work.
I have no idea why this is happening. One thing that comes to mind, but might be unrelated, i enabled cornering a while back following a tutorial on this forum... maybe i changed something i shouldn't? Can't explain why there is no error code or light.

What would you check to diagnose this issue?

 

[cairus]

Circuit diagram. The marking is the additional brake light. As far as I know, this is not monitored.

 

[mirceaculita]

Circuit diagram. The marking is the additional brake light. As far as I know, this is not monitored.

Where is this wiring coming from? Is it from one of the taillights or somewhere else?

 

[cairus]

BCM

 

[Walone]

Hello,

As the title says,

My third brake light stopped working. I have no lights on the dash and no errors with VCDS in central electronics. I tried the output test for brake lights and they do not work.
I have no idea why this is happening. One thing that comes to mind, but might be unrelated, i enabled cornering a while back following a tutorial on this forum... maybe i changed something i shouldn't? Can't explain why there is no error code or light.

What would you check to diagnose this issue?

Firstly, I think I would remove the lamp and check feed and earth with a multimeter.