How to replace a dishwasher's motor:

Common dishwasher motor and gasket Replacing a dishwasher motor
Note:
Disconnect the power source to your dishwasher before you conduct this or any other repair. Either unplug the unit from the wall outlet, remove the appropriate fuse from the fuse box, or flip the appropriate breaker in the circuit breaker panel.

Locate your dishwasher's motor. It will be found behind the lower kickplate/access panel. This panel will be held in place with either two or four screws. Remove the screws you find in order to remove the panel. It may be necessary for you to open the dishwasher door to remove the screws, but then close the door again to remove the panel.

Open the dishwasher door and remove the lower dishrack. Remove the spray tower and teh lower spray arm assembly. It will likely be held in place with a single bolt. If your dishwasher has a filter assembly below the spray arm, remove that too.

Disconnect the motor's two wire leads from the wiring harness. Then remove the drain hose from the pump. You can now lift the pump and motor assembly out of the base of the dishwasher. Remember to keep your work area as dry as possible to prevent dangerous electrical shocks.

Reverse the disassembly steps in order to install a new pump and motor assembly. With all components back in place, pour a gallon of water into the dishwasher's tub and do a check below the machine for leaks. If no leaks are present, restore power to your dishwasher and run the unit through a cycle. Do another check for leaks. If none are found, replace the lower kickplate/access panel.