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 LV1 from the PCB

Measurement:

Measure the resistance between the green wire
on LV1 (pin 1) and a suitable earth point.
Resistance should be greater than 1M Ohm.