Set Appliance State:

Set Multimeter to DC Volts Set meter to measure DC Volts
Isolate Mains Power to appliance as per TOPs P4
DHW Selector in Maximum (+) position
CH Selector in Minimum (-) position
ON/OFF Switch in ON position
Remove the 5 way plug (red sleeve) from the fan
WARNING! Mains voltage is expected during test, follow TOPs P4 live testing procedure
Mains Power On

Measurement:

Appliance will start self check sequence
Measure voltage across the plug.
Voltages should be approximately as in the table below.
+ ve- veDC Volts
BlackGreen5.0
Black Orange2.2
Orange Green2.8