Set Appliance State:

Mode selector switch to Off/Reset position
Set Multimeter to AC Volts Set meter to measure AC Volts
Turn Hot Water Tap On
Isolate Mains Power to appliance as per TOPs P4
Hot water temperature control set to maximum
Note:
To perform this test safely remove the ignition PCB from its cradle and refit in
the upturned position with the terminals exposed and facing the main PCB
Use insulation mat as necessary
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Measurement:

Mode selector switch to DHW position.
Allow fan to run and ignition sequence to commence.
Measure the voltage across connection 4 (blue wire) and connection 5 (brown wire)
on plug 1 (middle connector) on the ignition PCB.