As said the system is working normally, pump should run for a while when turned to position 1 and then stop, ABS light should also estinguish after a self diag in position 2, however this is a common problem which I have myself, never really bothered with it as it's never caused me bother.

It's when you are going about 5MPH then go to brake isn't it, the pedal goes hard and you get a noise?

My thought is it's caused by air being in the system, rather than a sensor fault as when it happens the ABS light never illuminates.

Martin