If you're dealing with a Whirlpool Duet Sport front load washer (also sold under the Maytag and Kenmore brands) that just beeps when you press the start button but doesn't lock the door or run, it can be tricky to figure what the problem is. The prime suspects are: CCU (central control unit), MCU (motor control unit), and the door latch assembly. Academy Fellow Trying to help offers this tip for checking the MCU to determine whether it's the cause of the problem or not. If it checks good, you have two other suspects to test but at least you've eliminated one of them! OTOH, if the MCU tests bad, you can buy the replacement MCU here with a one year, no-hassle return policy, look up your exact board by the model number of your washer.
Yes, there is a 3 wire blue harness that runs from the CCU (Central Control Unit) to the MCU (Motor Control Unit) I believe it is the M3 connector. Unplug that connector at either end and let it hang. Now hit start, if the unit locks the door and acts like it is going to take off on it's little merry way, you have a bad motor control board. Chances are with this disconected after a minute or so a code will pop, but you will already have your answer. At the moment of start the CCU looks for two signals, door lock and motor control. If it does not see what it likes it tripple beeps. Removing the harness eliminates the bad signal. It will lock the door now and sit there looking for the MCU signal. No signal is better than a bad signal! Make sure you ohm your motor to verify it is not shorted and the source of the blown board though!
Here's the MCU test technique illustrated:
and Brother PDuff shares this old tech tip for checking the CCU:
Old tech trick for checking CCU's was to unplug unit and plug back in. If you hear a click from the CCU then the CCU was usually ok. But I think these new CCU's are onto that trick. Still researching that switch at access panel. I don't know if it would cause a problem but it has attracted my attention. Will advise.