Set Appliance State:

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

Measurement:

Reset appliance as necessary.
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:
Voltage will only be present for approximately 45 seconds
after boiler is reset (or power is turned on), repeat as
necessary until test is complete.