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
Pull connector X5 back slightly to expose test points
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 X5 on the
harness from each wire listed in the table to the
black wire (pin 4) on the PCB X5 connector.
Voltages should be approx. as follows:
Lead
DC Volts
Pink (pin 6)
4.9v
Yellow (pin 5)
4.9v

Note:
Wires may be multicoloured.