A dishwasher performs different actions during a wash cycle. During the cycle, the arms at the bottom of the machine begin to spin, spraying water and soap around the unit to clean dishes. If the arms do not spin, the unit might not finish the cycle or will only clean some dishes. Spinning arm issues can be fixed, but it also might indicate a problem with the unit's timer motor.
Open the dishwasher door and inspect the arms for blockages. Pull out and food or dishes that might be blocking the arms.
Unscrew the cap of the spray arm by turning the cap clockwise. Lift the arm up and out. Clean the arm of any debris that might be keeping it from moving. Clean the base underneath the arm with a toothbrush.
Pull out the lower panel of the dishwasher to remove it. Put on gloves and find the motor underneath the unit. Turn its flywheel by hand to keep it from sticking. Turn on and test the unit.
If that did not resolve the problem, open the dishwasher's door by removing all screws from around it. Pry the door apart gently with a putty knife. Look for the timer motor. Look for the round motor housing on the timer motor. Follow the wires to the connecting terminals. Pull out the connectors and mark them so that can reconnect them properly. Set a digital multitester, a unit used for testing voltage, to the X1000 setting. Touch one probe to each wire. You should get a reading between 2,000 and 3,500. Replace the timer motor if you receive a different reading. Lift the unit out to replace it. Plug the wires into the appropriate connections on the new timer motor.