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
Boiler on/off switch ON
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Measurement:

Allow ignition sequence to commence.
Measure the voltage across pin 1 (black) and pin 2 (blue)
on the 12 way connector on the front of the PCB.
Expected voltage should be greater than 150 Volts DC.