Inlet water is controlled by a solenoid operated valve - it is relatively easy to change and is located where the external water pipe connects. There is no reason for a manufacturer to fit a "trip switch" to the circuit for this valve.
The machine's programmer should open this valve and close it when the correct volume of water has entered.
http://www.renovation-headquarters.com/householdrepairsdishwasher2.htm
Peccavi, June 2009
