Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Set Multimeter to Resistance Set meter to measure resistance
Gain access to PCB (use Insulation Mat as required)
Disconnect connector X4 from the PCB

Measurement:

Measure the resistance across the blue wires on connector CN4.
Resistance should be open circuit.
Turn hot tap ON.
Again measure the resistance across the blue wires on connector CN4.
Resistance should now be closed circuit (zero resistance).