Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Set Multimeter to Resistance Set meter to measure resistance
Remove connector X3 from the PCB

Measurement:

Test 1.
Measure for resistance across pins 3 (black) and 2 (blue) of connector X3.
Resistance should be approximately 9.1k Ohms.
Test 2.
Measure for resistance across pin 3 (black) of connector X3 and a suitable earth connection.
Expected resistance greater than 1 MOhm (or O.L).
Note:
Wires may be multicoloured.