Set Appliance State:

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

Measurement:

Test 1:
Measure the resistance between the two red wires
marked 7 and 8 on X6 connector.
Resistance should be approximately 45 Ohms or greater.
Test 2:
Measure the resistance between each of the red wires on X6 connector,
in turn, to a suitable earth point.
Resistance on each test should be greater than 1MOhm.