When a dishwasher cycle starts, it fills the tub with water. If there is not enough water in the tub, the dishes will be inadequately cleansed. If there is too much water, it may result in leakage. The water level may also prevent the dishwashing cycle from starting at all.
Check that the tub is filled with water to the proper level. When you start the dishwasher, the first thing that happens is water is released by the inlet valve into the tub. Listen as the tub is filled. When you hear the flow of water stop, open the dishwasher. The water level should be just below the bottom of the float. If the water level is too low, the inlet valve is probably the culprit. However, water could be draining even as it is filling. Refer to the diagnostic table section labeled "Dishwasher does not fill with water...."
If the water lifts the float all the way up or the float is submerged, the water level is too high. Overfilling is likely a problem with the float or float switch.
If there is enough water at the beginning of the cycle, let it run through to the wash cycle. Near the middle of the wash cycle, stop the dishwasher and check the water level again. The water level should be about the same as before. If it is significantly less, water may be draining out prematurely. Refer to the diagnostic table section labeled "Dishwasher does not fill with water...."