Set Appliance State:

Set Multimeter to Resistance Set meter to measure resistance
Isolate Mains Power to appliance as per TOPs P4
Disconnect connector ST16 from the PCB

Measurement:

Test 1:
Measure resistance between the brown wires (pins 12 and 13) at connector ST16.
Test 2:
Measure resistance between the green wires (pins 19 and 20) at connector ST16.
Resistance should be approximately 77 Ohms on both tests.