Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
DHW Demand
DHW Selector in Maximum (+) position
CH Selector in Minimum (-) position
ON/OFF Switch in ON position
Set Multimeter to DC Volts Set meter to measure DC Volts
Use Insulation Mat as required
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Measurement:

Measure voltage across connection 2 (black wire)
and connection 6 (green wire) on connector X2.
Expect approx. 2.2V DC.