Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Set Multimeter to Resistance Set meter to measure resistance
Disconnect connector X6b from the PCB

Measurement:

Inspect the condition of the harness between
the diverter valve and the PCB.
Check for continuity between each of the three wires in turn from the diverter valve to pins 1, 2 and 3 at X6b connector on the PCB.
Note:
If a white board is fitted connector is in same location but is called X6 instead of X6b.