Set Appliance State:

Mains Power Off
Gas Off
Set Multimeter to AC Volts Set meter to measure AC Volts
Selector Switch in summer position
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Measurement:

Whilst holding in ignition button, measure mains voltage on J4 pin 1 (red N) and 2 (brown L).
Note:
Before ignition button is pressed approx 120V AC will be seen.