Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Set Multimeter to Resistance Set meter to measure resistance
Disconnect X2 connector from the PCB

Measurement:

Test 1:
Measure the resistance between the two
red wires on X2 connector.
Resistance should be approximately 70kOhms.
Test 2:
Measure the resistance between each of the two
wires and a suitable earth point.
Resistance should be greater than 1M Ohm on both tests.