Set Appliance State:
| Isolate Mains Power to appliance as per TOPs P4 |
Set Multimeter to Resistance 
Disconnect connector M4 from the main PCB
Measurement:
Test 1:
Measure the resistance between the brown wire (C) and the light blue wire (B) at M4.
Resistance should be approximately 45Ω.
Test 2:
Measure the resistance between the brown wire (C) at M4 to a suitable earth point.
Resistance should be greater than 1MΩ (or O.L)
Measure the resistance between the brown wire (C) and the light blue wire (B) at M4.
Resistance should be approximately 45Ω.
Test 2:
Measure the resistance between the brown wire (C) at M4 to a suitable earth point.
Resistance should be greater than 1MΩ (or O.L)
Isolate as per TOPs P4
and refit as necessary