Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Set Multimeter to Resistance Set meter to measure resistance
Remove the M4 connector from the PCB

Measurement:

Test 1:
Measure the resistance between pins 21 (grey)
and pin 22 (brown) at the disconnected plug.
Resistance should be approximately 1.6kOhms.
Test 2:
Measure the resistance between pins 23 (yellow)
and pin 24 (white) at the disconnected plug.
Resistance should be approximately 2.8kOhms.