Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Set Multimeter to Resistance Set meter to measure resistance
Remove connector CN13 from the PCB

Measurement:

Test 1:
Measure the resistance across pin 68 and pin 64 on connector CN13.
Expected resistance greater than 1 MOhm (O.L is greater than 1Mohm).
Test 2: Resistance to Earth
Measure the resistance between pin 68 on connector CN13 and a suitable Earth point.
Expected resistance greater than 1 MOhm (O.L is greater than 1Mohm).