Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Set Multimeter to Resistance Set meter to measure resistance
Remove connector CN4 from the PCB

Measurement:

Test 1:
Measure the resistance between pin 1 (blue)
and pin 2 (brown) on connector CN4.
Expected resistance approximately 29 ohms.
Test 2: Resistance to Earth
Measure the resistance between pin 1 (brown)
on connector CN4 and a suitable Earth point.
Expected resistance greater than 1 MOhm.