FIS Error: Brake Light Malfunction

Hello!

Okay, I've already received my first error message with my "new" A3. The following happened: An unpleasant beeping sound from my FIS (Multi-Function Instrument Display) was accompanied by a prominent "BRAKE LIGHT" warning. I immediately started troubleshooting. Of course, the problem couldn't be solved by simply replacing a bulb, as all of them were working perfectly.
According to the error database, the brake light sensor or the brake pedal sensor might still be defective. However, this should occur in conjunction with an error message, so I took my laptop home from work (again). However, I couldn't do this until a few days later, and by then the warning message had disappeared, and everything was working perfectly (although the flashing indicator light had also disappeared before...). There was also no error message at that point.
Since the entire issue hadn't appeared for the whole last month, I was hoping it had resolved itself.

Today, the fun started again. BRAKE LIGHT + flashing filament (but not always!). By chance, I then noticed that the BRAKE LIGHT message also disappeared when I turned off the low beam headlights.
Headlights back on: --> BRAKE LIGHT turns on again...
Also, the message disappears when I press the brake pedal, and it reappears (along with that awful beeping sound }) when I release the brake pedal...
Does this mean the brake light sensor is still faulty, or is there something else more serious going on? What does this have to do with the low beam headlights?
I won't be able to read the error codes until in two days, but maybe someone has an explanation in the meantime?
It's just great that every time I apply the brakes, the beeping sound puts a bit of strain on my nerves.

Sure, here is the translation of the text from German to English:

"MFG" is an abbreviation for "mit freundlichen Grüßen," which means "best regards" or "sincerely." It is commonly used in German-language emails and letters.

Perhaps you should read your vehicle's manual and then check your brake light bulbs.

Quote:

Of course, the problem couldn't be solved by simply replacing a light bulb, as all of them were working perfectly.

Thank you, I already knew that.

I read that. The question is, which bulbs did you check? Did you also check the third brake light? Did you really replace ALL the bulbs?

Are you sure it turns off when the low beam headlights are switched off, or does it turn off with the parking lights?

I had a similar problem with a Golf IV; it turned out that the bulb in the socket was a single-filament bulb instead of a dual-filament bulb.

Hi!
Okay, now I've found that darn bug .

After stumbling upon "Martha's" post using the search function, I finally found the right track.

Here is the post: https://community.dieselschrauber.org/en/viewtopic.php?t=6787&highlight=bremslicht+defekt

@chli1976: What you said about the single-filament and double-filament bulb is almost correct , except that in my case (just like with Martha), the smaller filament melted onto the larger filament because it touched a contact.
Both of them worked perfectly independently of each other. That's why I didn't find anything wrong during the first inspection of the light bulbs - all the bulbs were lit.

When the low beam headlights were turned on, the error current, which was caused by the melting of the larger brake light filament, was detected, and the error message "BRAKE LIGHT" was displayed. However, the low beam headlights still functioned properly because the filament itself was not damaged.
When the brake is applied, the large indicator light illuminates, and the onboard computer "thinks" that everything is working again and retracts the error message. When I then release the brake, there is again an error current and an error message (plus a pleasant beeping sound ).

That's why the error memory was empty, and the brake pedal and brake light sensors are functioning correctly.

Well, that's about it... I'll post a picture of the culprit later this evening.

@Besswerwisser: so, your approach was actually in the right direction .

MFG[/quote]

wbuchi82 wrote:

@Besswerwisser: so your approach was actually in the right direction

It's funny that you still get negative karma points here... great system.

Here's what it looks like:

" color="red">Bitte keine Links zu externen Dateihostern! a) nerven die zusätzlich notwendigen Klicks, b) Wartezeit, Werbebanner/Werbepopups und notwendige Registrierungen, c) ist nach einiger Zeit die Datei weg und das Thema für andere Leser nutzlos!

Bitte nutze 'Attachment hinzufügen' bzw. das Upload Forum hier.