There is a float switch inside your dishwasher that is usually to the left and is covered by a plastic piece that you can unscrew. Then take the float switch out and make sure it is clean and clear of all debris, and that it is working smoothly in its place. If its not that, then there is a switch underneath the float that you can only get to by accessing the underneath. To check that switch, you can take a multi-meter with ohm checking on it and see if the switch is operational by applying the leads from your multi-meter to each of the terminals. You should get nothing while depressed and it should ohm out if pressed. It could possibly be reversed, but aslong as you dont have a constant ohm or visa-versa, your okay. There is also a solenoid on the motor itself that you can do this same check on. It opens the flaps to let the water out when the timer calls for it. Last but should be first, make sure your hose that runs from the dishwasher isnt kinked or clogged in anyway. Always disconnect the power supply before doing any electrical. Hope this helps.