I'm not an expert but here goes. Looked at the motor diagram and see a solenoid (5) that looks like it controls the flapper to the outlet valve. So if you have power to the solenoid at the end of cycle and the solenoid windings show open then the noid is bad. If power, and good noid then make sure the guts of the noid have free motion including the little plug/flapper on the outlet valve inside the bottom of the dishwasher.
I'd check the windings first then the mechanism for function by hand. Make sure all power is off before probing around. If neither of these are the culprit then look to see if there is power to the solenoid during the "drain cycle". If no power then it's a signal problem with the control panel or a damaged wire somewhere.