Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Set Multimeter to DC Volts Set meter to measure DC Volts
NO demands for CH or HW
Disconnect DHW thermistor at harness lead
Gain access to main terminal box
On/Off Switch ON
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Measurement:

Measure the DC voltages as follows between the Fan connector and the Neutral (blue) at the incoming mains connector
The voltages should conform approximately to the table below:
WireDC Volts
Pink110
Yellow 94
Black110