Set Appliance State:
| Isolate Mains Power to appliance as per TOPs P4 |
Set Multimeter to Resistance 
Disconnect connector X3 from the main PCB
Measurement:
Test 1:
Measure the resistance between pins 1 and 2 (brown and blue) at the disconnected connector.
Resistance should be approximately 780 Ohms.
Test 2:
Measure the resistance between pin 1 (brown) at the disconnected connector to a suitable earth point.
Resistance should be at least 1M Ohm.
Measure the resistance between pins 1 and 2 (brown and blue) at the disconnected connector.
Resistance should be approximately 780 Ohms.
Test 2:
Measure the resistance between pin 1 (brown) at the disconnected connector to a suitable earth point.
Resistance should be at least 1M Ohm.
Isolate as per TOPs P4
and refit as necessary