Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Set Multimeter to Resistance Set meter to measure resistance
Remove connector X12 from the PCB

Measurement:

Test 1. Measure for resistance across pins 17 (blue) and 16 (brown)
of connector X12.
Expected resistance approximately 160 ohms or greater.
Test 2. Measure for resistance across pin 16 (brown) and a suitable earth connection.
Expected resistance greater than 1Mohm.