Set Appliance State:

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

Measurement:

Test 1:
Measure the resistance between the red and purple wires.
Expect either 6.6 kOhms or open circuit.
Test 2:
Measure the resistance between the red and grey wires.
Expect either 6.6 kOhms or open circuit.
Are the resistances measured as expected.