At the end of the “wash” cycle, the pump enters the “drain” mode. The hot, soapy wash water is flushed out and drained.
The pump drains water from the tub in one of two ways. See the illustrations below.
In some “direct-reversing” designs, the motor reverses direction and a separate impeller pumps the water out.
In other designs, a solenoid-controlled valve opens to allow the pump to discharge to the drain line.
The timer controls the direction of the motor or the opening of the drain valve.
After the drain cycle, the tub fills again, with clean hot water.
Note that the dishwasher also operates in the “wash” mode during the “rinse” cycle. That is, it’s taking water from the bottom of the tub and spraying it at the dishes. The only significant difference is that it is clean, clear water; no detergent is being released during the “rinse” cycle.
However, some dishwashers DO open rinse agent dispensers; chemicals that help to diminish spotting when drying. The timer controls when this occurs. In most designs, the dispenser is opened either by a solenoid or by a bi-metallic trigger. In some machines, GE used a cam on the timer to trip open the dispenser.