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)
Disconnect connector X6 from the PCB

Measurement:

Measure the resistance between the white wires on X6, marked 16.1 and 16.2.
The resistance should conform approximately to the table below: