F28 = SERIAL COMMUNICATION ERROR
The communication between the Central Control Unit
(CCU) and the Motor Control Unit
(MCU) cannot be sent correctly.Possible Causes/Procedure1
. Unplug washer or disconnect power.2
. Check wire harness connections to the MCU, the motor, and Central Control Unit (CCU).
– Check connections of the CCU board within the housing.
– Make sure all grounding switches are engaged.3
. Check the drive system for any worn or failed components.4
. Plug in washer or reconnect power.5
. Verify CCU operation by running a Diagnostic Test or any cycle.6
. Check the MCU by looking for operations of the drive motor.7
. Check the drive motor for powered rotations.8
. Check that the serial harness at the MCU is not mounted upside down.
The wires should be to the left when facing the MCU connectors.
I have attached a copy of the tech sheet for you.WFW8400TW00 Parts Diagram
CCU Part # W10205841
MCU Part # W10163007