Inside the machine is a pressure switch ,with a tube,
one end of the tube connects onto the tub,the other,onto the switch.
This device basically meters the water allowed into the tub,the pressure created by the water at a certain level point activates the switch and a signel is received by the pcb,which sends the correct voltages to the water intake valves and drain pump.
On some occasions the tube from the tub to the switch becomes blocked,
unblocking it by blowing down it sometimes helps.
If clearing the tube doesn't fix the overfill issue, then the pressure switch is likely at fault and needs replacing.
If there's a problem with either hot or cold inlet valves,then water enters the machine without any control,
the pressure switch detects this and the pump will auto try to empty the tub,
as yours isn't filling and draining simultaneously then the fault is pressure switch related.
if you have a multimeter you can test the switch by measuring the resistance across the terminals whilst blowing town the tube.
No change in the reading would suggest the switch is faulty.
Hope this info helps and remember to isolate the power to the appliance before you start your investigation,.
paul, March 2012
