I've got a 2004 polo 1.4 which shows a brake wear indicator on the dash combined with a beep at startup.

I've checked all 4 brakes, inner and outer pads, and all are like new.

The wear indicator is only on the rear (passenger/right side). The sensor, wire and connection is tightly fitted with no visible damage.

I've measured the sensor and it shows 1.7 ohm and continuity.
I've measured at the connection (car side not sensor side) and it shows +12V (pink) on one pin and nothing on the other (yellow).

I tried shorting the two pins with no effect (wear indicator still shown). Trying shorting the wires further up (under dashboard) thinking maybe the connection is duff, with no effect.
Checked all the fuses (although there shouldn't be any fuse for the brake wear indicator) and all are fine.

So now i'm thinking that I have to check the other end, however it seems very unlikely that the connection is loose there.

So two questions:
1. Where is the other end connected ? To the ECU ? and where is the location of it (engine compartment or under dash)?
2. Any other ideas to what to check ?