To troubleshoot a KitchenAid dishwasher that isn't draining, check the drain hose, drainage basket and sump for food particles. The drain pump and check valve are also common causes for poor drainage.
Begin troubleshooting the dishwasher by checking the garbage disposal for proper operation. If the garbage disposal is not draining properly, small pieces of food may be located in the hose that connects to the garbage disposal under the sink. Turn the power off to the dishwasher and garbage disposal, and remove the hose. Allow water to run through the hose until it is cleared, and clean the check valve thoroughly before reattaching the hose. The check valve can also become stuck, preventing the water from draining properly. Install a new check valve if necessary.
The drainage basket or sump can also become clogged by small food particles. Remove the drainage basket and clean it thoroughly, then use a straight wire to clean the sump. Replace the drainage basket, and check the operation of the dishwasher. If standing water is present after cleaning, the dishwasher may require further repairs.
The drain pump may require repairs or replacement if the dishwasher isn't draining after cleaning the drain hose, check valve and sump. Check the drain pump to determine whether the belt has slipped off or broken, and replace the belt if needed. A new drain pump should be installed if other repairs have been made and the problem has not been resolved.