Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Set Multimeter to Resistance Set meter to measure resistance
Remove connector X5 from the PCB

Measurement:

Test 1:
Measure the resistance between pin 12 and pin 11 on connector X5.
Expect a resistance of 1 Mohm or greater.
Test 2:
Measure the resistance between pin 11 and pin 10 on connector X5.
Expect a resistance of 1 Mohm or greater.
Test 3:
Measure the resistance between pin 12 and pin 10 on connector X5.
Expect a resistance of 1 Mohm or greater.