Set Appliance State:

Set Multimeter to Resistance Set meter to measure resistance
Isolate Mains Power to appliance as per TOPs P4
Disconnect connector PL3 from the PCB.

Measurement:

Measure the resistance between the terminals with the red wire and white wire of the disconnected connector. Do NOT test at the PCB socket.
Expect the resistance to be approximately 13 KOhms.