Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Set Multimeter to DC Volts Set meter to measure DC Volts
Turn Hot Water Tap On
Remove DC electrical connector from fan assembly and make safe
Preheat OFF
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Measurement:

Reset boiler if required.
Measure the DC volts at the PCB connector X8 on the
harness from each wire listed in the table to the
black wire (pin 3) on the PCB X8 connector.
Voltages should be approx. as follows:
Lead
DC Volts
Pink (pin 5)
2.8v
Yellow (pin 4)
4.9v

Note: To ensure a good connection is made use the small test points on the PCB just below the connector.