Set Appliance State:
Isolate Mains Power to appliance as per TOPs P4
Gain access to PCB (use insulation mat as necessary)
Disconnect connector M3 from the PCB
Gain access to PCB (use insulation mat as necessary)
Disconnect connector M3 from the PCB
Measurement:
Measure the resistance between the two brown wires of connector M3.

Isolate as per TOPs P4
and refit as necessary