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 the resistance between pin 1 (brown)
and pin 3 (blue) on connector X3.
Test 2.
Measure the resistance between pin 2 (black)
and pin 3 (blue) on connector X3.
Expected resistance on both tests should be
approximately 8.5 KOhms or greater.
Test 3.
Measure the resistance between pin 1 (brown)
and pin 2 (black) separately to a suitable earth.
Expected resistance on each test greater than 1 MOhm.