Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Set Multimeter to DC Volts Set meter to measure DC Volts
CH Demand
Pull connector X6 back slightly to expose test points
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Measurement:

Measure the voltage between pin 4 (Blue) and pin 5 (Black) at connector X6 on the PCB.
Voltage may fluctuate but should be approximately 2.5V DC.
Note:
Wires may be multicoloured.