Set Appliance State:

Set Multimeter to Resistance Set meter to measure resistance
Isolate Mains Power to appliance as per TOPs P4
Remove the 4 wire connector from X6 on the PCB

Measurement:

Test 1:
Measure the resistance between pins 1 and 2 on the 4 wire connector removed from X6 on the PCB.
Expect a resistance of approximately 1.6 KOhms.
Test 2:
Measure the resistance between pins 3 and 4 on the 4 wire connector removed from X6 on the PCB.
Expect a resistance of approximately 2.8 KOhms.
Test 3:
Measure the resistance between pin 1 and a suitable earth.
Expect a resistance of 1 MOhm or greater.
Test 4:
Measure the resistance between pin 3 and a suitable earth.
Expect a resistance of 1 MOhm or greater.
Are the resistances measured as expected?