|If your Dishwasher is not Draining check the following
On some dishwashers that have a filter (screen) along the back wall of the tub have a piston valve. The piston valve commonly causes dishwashers not to pump out. if your dishwasher does have a filter, remove it. Now remove the piston valve located in the center behind the filter. Now to check the piston valve, press up on the spring. Once done the piston should stop up the hole in the top of the valve. When a piston valve, is bad the piston dissolves to the point that it can no longer stop up the hole, in this case replace it.
Another common problem on some dishwashers that will cause it not to drain properly is the drain solenoid. To check this, first disconnect power from dishwasher then remove the bottom panel of dishwasher. Once off, you should see the drain solenoid attached to the main pump then reach under the dishwasher and push down on the solenoid. If it will not move down it is bad and needs replacing. If it will push, down most of the time it is good but not always so follow these steps as well. Reconnect power to dishwasher, now start the dishwasher in to a cycle. If you have a mechanical timer turn it slowly until the solenoid energizes. If you turn the timer all the way around and the solenoid never energizes replace the solenoid. If you have an electronic control, start the dishwasher and wait a few minutes then push start/reset then the drain solenoid should energizes, if not replace the solenoid. At times the timer will cause this part to go bad especially if its melted or frozen down. So you may have to replace the timer as well. This solenoid is reviewed in the following video this tutorial may also help.
If your dishwasher is not draining properly, the check valve may be your problem. The check valve will be on some dishwashers with both a separate drain pump and a drain solenoid (note if you do not have both you will not have a check valve). The check valve will be located where the black hose connects to the drain pump. To access the check valve, you must first remove the water from the dishwasher. A Wet-Vac works well. After the water is out, disconnect power to dishwasher. Now remove the dishwasher from under the cabinet. Now remove the black hose (even though you removed the water you will still have water in the pump so be ready).Once off you should see the check valve. It’s the little red rubber flap. If it is torn off, the flap may have gone down the drain but you still should see the red ring left behind, in this case replace the valve. Sometimes the check valve will swell up and hang in the pump, if so replace it.
If your dishwasher is not draining properly, the drain pump may be your problem. As stated before, not all dishwashers will have a drain pump. To check this, First check to see if it is getting power. You should have 120 volts when the dishwasher is put into a drain cycle. If you have power and the pump does not run remove the pump and check for obstructions if none found replace the pump. The following video will walk you thru one type and the tutorial will cover another.
If your dishwasher is not draining properly, the drain hose may be stopped up. To check, remove all the water from tub. A Wet-Vac works well for this. After the water is gone remove the drain hose (even though you removed the water you will still have water in the pump so be ready) from the house plumbing and the dishwasher. Check for obstructions and remove. If you just installed a new garbage disposal check that the metal knockout was removed. This is covered in our dishwasher installation video. Check the air gap or high loop if this is not right your dishwasher will siphon water back into it.