Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Set Multimeter to Resistance Set meter to measure resistance
Remove connector 20 from the PCB

Measurement:

Test 1.
Measure the resistance between the brown and blue pins on connector 20.
Expected resistance 180 ohms or greater.
Test 2.
Measure the resistance between the blue and earth pins on connector 20.
Test 3.
Measure the resistance between brown and earth pins on connector 20.
On test 2 and test 3 expected resistance greater than 1 Mohm.
Note.
A reading of O.L on tests 2 and 3 is acceptable as this is greater than 1 MOhm.