Set Appliance State:

Gas Off
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 set to DHW
DHW temperature control set to MAX
Preheat switched OFF
Note. Slightly move connectors until PCB connection strips
are exposed for voltage measurement
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Measurement:

Reset appliance as necessary.
 
Measure the AC voltage between pins 4 and 5 on connector X3 on the PCB.
 
At 20 second intervals mains voltage should be measured
for 3 seconds as power is sent to the spark generator, this
will be repeated 5 times until lockout occurs.
 
Is the voltage measured as expected?
 
Notes:
1. Timings quoted are approximate.
2. Reset appliance and repeat test as necessary until outcome is determined.