Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Set Multimeter to Resistance Set meter to measure resistance
Gain access to PCB (use Insulation Mat as required)
Summer / Winter switch set to winter (pushed in)
Disconnect M6 from the PCB

Measurement:

Measure the resistance between the two pink wires at M6.
Resistance should be short circuit (zero resistance).