Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Set Multimeter to AC Volts Set meter to measure AC Volts
Turn Hot Water Tap On
Gain access to PCB (use Insulation Mat as required)
Selector switch to DHW position
CH temperature selector to minimum
DHW temperature selector to maximum
WARNING! Mains voltage is expected during test, follow TOPs P4 live testing procedure
Mains Power On

Measurement:

Allow fan to run and ignition sequence to commence.
After approximately five seconds, measure the voltage at connection 2 (left hand blue lead) and connection 4 (left hand brown lead) at connector A1 on the PCB.
Voltage will only be present for approximately 10 seconds. As burner will not ignite, boiler may go to lockout.