The Whirlpool W10859566 is an essential component of your dishwasher, serving as a door latch switch. This switch is critical to ensure the dishwasher's safety and efficiency. The switch is located near the door latch and detects if the dishwasher door is securely closed. When the door is closed, the switch activates, signaling to the dishwasher's control panel that it is safe to start the wash cycle. In contrast, if the door remains open, the switch will not trigger, preventing the dishwasher from beginning and perhaps overflowing. A defective door latch switch can cause a variety of problems, including the dishwasher failing to start, leaking water, or continuing to operate even while the door is open.