ML320 Brake Wear Sensor light AND Audible warning

[andrew_zaf]

ML320 Build Date October 2000. Brake wear sensor started to light up intermittently then more often and in the last week for several times, an audible pitch noise sounded when the wear sensor(both handbrake and sensor lights) lit up.

Bought a set of new front brake pads - with new sensor wire pre-fitted to the passenger side pad set and installed these new pads to the front 2 wheels. (Old pads had over 1/4" left on them).

Fitted the pads making sure the sensor wire clipped in ok and was not damaged in the fitting process.

Driving the car now - the sensor light (both brake and wear sensor light) still light up intermittently.
Today I had to brake hard and almost engaged the ABS and the sensor lights lit up and the audible pitch sounded at the same time.

Brake fluid is up to the full level.

Please, gents, what do you think I should look for?