Turn off the power to the dishwasher. Turn off the water supply at the wall.
Remove the access panel at the bottom front of the dishwasher. Pull the dishwasher out from the cabinet.
Locate the inlet valve. The inlet hose is smaller than the drain hose, and it's generally located closer to the front of the dishwasher.
Disconnect the wires from the inlet valve's two terminals. Clip the continuity tester to one terminal, and touch the tester's probe to the other terminal. If the tester lights up, the solenoid is working properly, and you need to replace the valve screen. If the tester does not light up, the solenoid is not working, and you need to have a professional repair it.
Place a shallow pan under the inlet valve to catch any water that drips out of the inlet tube. Squeeze the clamp around the inlet tube, and slide it away from the valve. Pull the inlet tube off of the valve.
Locate the water supply tube attached to the bottom of the inlet valve. Loosen the nut at the top of the supply tube with a screwdriver, and detach the tube from the valve.
Loosen the screws on the valve's mounting bracket with a screwdriver, and pull the valve away from the side of the dishwasher.
Locate the screen on the bottom of the valve where the water supply tube was connected. Pry the screen out of place with a small screwdriver. Push the replacement valve screen into place. Reassemble the dishwasher by reversing the above steps.