Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Set Multimeter to Resistance Set meter to measure resistance
Remove connector CN302 from the PCB

Measurement:

Test 1. Measure for resistance across pins 1 (blue) and 3 (brown) of CN302.
Expected resistance approximately 160 ohms or greater.
Test 2. Measure for resistance across pin 3 (brown) and a suitable earth connection.
Expected resistance greater than 1Mohm.