Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Set Multimeter to Resistance Set meter to measure resistance
Remove connector X25 from the PCB

Measurement:

Test 1:
Measure the resistance between pin 1 (Blue)
and pin 2 (Red) on connector X25.
Expect approximately 178 ohms.
Test 2:
Measure the resistance between pin 1 (Blue) and
a suitable earth.
Expected resistance greater than 1 MOhm.
Test 3:
Measure the resistance between pin 2 (Red) and
a suitable earth.
Expected resistance greater than 1 MOhm.