Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Set Multimeter to Resistance Set meter to measure resistance
Remove the connector X2 from the PCB
Remove the plug from the diverter valve

Measurement:

Measure the resistance of the 4 wires from the diverter valve plug to pins 7, 8, 15 and 16 on connector X2.