Parking assist malfunction

Hello everyone,
My parking assist system is no longer beeping.
VCDS indicated that a sensor was faulty, which I replaced. Now, all 4 sensors are providing correct values, but there's still no sound.

Error memory is empty.

Could you tell me which PIN output on control unit 8Z0 919 283 (parking assist control unit, manufacturer SWF) is responsible for the sound? Then I could check if the control unit is faulty or if the speaker is defective.
"Thank you!!"

I would measure the voltage at the beeper. Mine was also defective on my A4. It is highly likely that the wire connecting to the diaphragm inside the device has broken.

Better late than never: The solution.

The speaker was defective. I was able to measure the output signal in the range of 0.0...V.
I tested it using an old speaker from a walkie-talkie.