Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Set Multimeter to Resistance Set meter to measure resistance
Remove connector CN2 from the PCB

Measurement:

Test 1. Measure for resistance across pins 1 (blue) and 4 (brown) of CN2.
Expected resistance approximately 160 ohms or greater.
Test 2. Measure for resistance across pin 4 (brown) and a suitable earth connection.
Expected resistance greater than 1Mohm.