T5 Brake Fluid MIL: No Function (Solution)

Hello everyone!

The T5 from the signature you mentioned really doesn't miss an opportunity to make our lives difficult and to cause me a lot of trouble.

Here's a brief summary beforehand:
If the brake fluid level is too low, NO warning message will be displayed.
Even when the connector is disconnected from the level sensor on the brake fluid reservoir, NO warning message is displayed.
Even after driving for several kilometers, the silent "parking brake light" remained on, and it should have also emitted three beeps.
It's equipped with a basic combination instrument cluster without MFA/FIS (but it does have a compass, coolant temperature, and fuel level display *g*).
When the coolant sensor is disconnected, the corresponding MIL (Malfunction Indicator Lamp) will illuminate after 5 seconds.

Detailed explanation of the process:
"Finally changed the brake fluid with some help (from a cyclist *g*). Started the HR (rear heating) in the conventional way with the engine running, without using any other aids (and without using VCDS)."
Instruction for pedal operators during brake system malfunction: Stop applying the brake pedal; do not attempt to refill the brake fluid.
After pumping out about 250ml of breast milk (we were still HR!), I asked about it - no milk, okay, let's continue. Then, when I was about to reach 300ml, the brake caliper started rubbing against something - very, very nice...
Nachgeguggt: BF-Behälter leer, klar. But NO MILK!!
Topped up, further vented, and this time, I added another 150ml.

Now I've unplugged the connector on the BF container to rule out any (potentially) programmed delay of the MIL.
The monitoring must be designed to be "fail-safe," meaning that even if the connection(s) are interrupted, an error should always be reported. ...here: nothing...
Personally, I don't know of any car that was different from the ones I've seen since I held a Lego toolbox in my hands.
The most important indicator in a vehicle silently fails to perform its function, which I consider to be extremely problematic.

What could be the reason for that?
Can the "brake system malfunction" MIL (Malfunction Indicator Lamp) be cleared?
So far, in the AI system, I've only removed the seatbelt warning, then removed and re-added the brake pad wear indicator, and haven't messed with anything else.
Is there a module in the AI system where one could read the status of the BF sensor, or is it like the generator MIL, with no diagnostic "logic" whatsoever?

Please say thank you in advance for your tips!!

Best regards from Munich!

The sensor needs to have continuity for a message to be triggered.
So, that's completely correct: If a cable is broken somewhere, there's never any notification.

Sad, but unfortunately true.

To put it bluntly, is the lamp itself okay?

Enjoy your meal together!

Bro, thanks for the amazing answer.
So, once again, we're going back to the Stone Age because a transistor costing just 0.3 cents is considered too expensive to use as an inverter, or because people are too lazy to implement a well-designed logic program?!
While one might argue that the savings of 1.50 EUR by reverting from dynamic oil pressure control to an oil pressure switch could be justified commercially, especially in a large production run, the fact that cost-cutting measures are now being implemented in safety-critical areas truly makes me lose faith.
Since I was confident that it was a "fail-safe" circuit, I didn't bother to connect the measuring device, but I'll probably have to do that and report back...

Klaui, thank you very much to you as well!
The T5 has the additional feature "parking brake," which can be used to test the indicator light .

Best regards from Munich!

Hello everyone!

Here's the solution:

TDI-GTI-4-Motion wrote:

The sensor must have continuity for a message to appear. So, that's completely correct: If a cable is broken somewhere, there's never any notification. Sad, but unfortunately true.

...and that's exactly how it is: When the connector is bridged, the MIL (Malfunction Indicator Lamp) comes on, but with a delay, not immediately.

Therefore, the (swimming-)switch in the BF container is broken. How long it has been broken is something VW will not care about.

Thank you very much for the valuable tip!!

Best regards from Munich!

EDIT: Ausgleichsbehälter f. Bremsflüssigkeit, Teile-Nr.: 7E0 611 301 B (wurde bereits geändert!!), ca. 30,00 EUR zzgl. MWSure, here is the translation of the text from German to English:

"St"
Order together: 2 x plugs, part number: 357 611 817, price per piece approx. €3.30 plus VAT.