The two thin wires are to count the revolutions of the motor and so calculate the change in pad thickness (wear) there is a hall sensor in the motor housing and these wires connect to that, it gives a small 'blip' signal when a magnet passes by. (A bit like ABS wheel speed sensor I presume).
As it was not very reliable, they went back to wear sensors in the pads on other models.
There is a thought that the A6 EPB module is the same except for ignoring this wear input, therefore may be more reliable and you can just rely on your eyes for the pad wear.
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