Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Set Multimeter to Resistance Set meter to measure resistance
Disconnect connector HV2 from the PCB

Measurement:

Test 1:
Measure resistance across
Pin 1 (Red) and Pin 2 (Blue) on HV2
Expect resistance greater than 1M Ohm.
Test 2:
Measure resistance between each wire -
Pin 1 (Red) and Pin 2 (Blue), and a suitable earth point.
Expect resistance greater than 1M Ohm on each wire.