Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Set Multimeter to DC Volts Set meter to measure DC Volts
CH Demand
Gain access to PCB (use Insulation Mat as required)
CH temperature control set to MAX
Remove connector 35 from the PCB and make safe
Remove connector 54/11 (Spark Generator) from the PCB and make safe
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Measurement:

Reset appliance if required.
Allow self-check to complete and ignition sequence to commence.
Measure for DC voltage across pins 1 and 3 where connector 35 was fitted.
Expected voltage approximately 330 Vdc.
Ensure a good connection is made or misdiagnosis will occur.
Note.
Voltage will only be present during the sparking phase of ignition (approximately 5 seconds), the boiler will enter lockout after 3 attempts of ignition, approximately 40 seconds between each attempt, reset as required until test is complete.