Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Set Multimeter to Resistance Set meter to measure resistance
Remove connector X12 from the PCB

Measurement:

Test 1.
Measure resistance across the red & black terminals of connector X12.
Expected resistance approximately 1ohm, remember to take meter leads into account.
Test 2.
Measure resistance across the brown & blue terminals of connector X12.
Expected resistance approximately 100 ohms, remember to take meter leads into account.