This DW has the horizontal motor that reverses for wash or drain.

Be sure the motor is stopping to reverse for drain, if so there is no electrical-timer problem.

Check for a clogged air-gap if one was used, then remove the lower panel and check for a clogged drain check valve [ its the plastic elbow where the drain hose connects ]

Other than these things the pump assembly could have a bad drain valve diaphragm, it is a rubber part that is under a white plastic cover on the back of the pump, you will either have to remove the motor and pump assembly to get at it or remove the entire DW to gain access.

John L.