Set Appliance State:
| Isolate Mains Power to appliance as per TOPs P4 |
Set Multimeter to Resistance 
Disconnect connector X10 at the PCB
Measurement:
Measure the resistance across connector X10 as per table below:
| Black test probe | Red test probe | Resistance |
| Black | White | 5.9kOhms or open circuit |
| White | Red | 5.9kOhms or open circuit |
Isolate as per TOPs P4
and refit as necessary