Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Set Multimeter to Resistance Set meter to measure resistance
Remove connector to diverter valve motor
Disconnect connector LV2 from the PCB

Measurement:

Check for continuity (zero resistance) of each wires in turn running between LV2 connector (connections 10,11,12 & 13) to the corresponding connection on the diverter valve motor connector.
Also inspect the harness for good overall condition.