Set Appliance State:
Set Multimeter to DC Volts 
Turn Hot Water Tap On
| WARNING! - Mains voltage is expected during test follow TOPs P4 live testing procedure |
Measurement:
Allow fan purge to complete (2 minutes).
Allow fan to run and ignition sequence to commence.
Measure the DC voltage between connector X12 and a suitable earth during the ignition sequence, as the burner ignites the voltage should drop from 4.3 vdc to 3.5 vdc or less.
Does the voltage behave as described above?
Note:
This test may need to be repeated several times to confirm the result, if the appliance locks out reset as necessary.
Allow fan to run and ignition sequence to commence.
Measure the DC voltage between connector X12 and a suitable earth during the ignition sequence, as the burner ignites the voltage should drop from 4.3 vdc to 3.5 vdc or less.
Does the voltage behave as described above?
Note:
This test may need to be repeated several times to confirm the result, if the appliance locks out reset as necessary.
Isolate as per TOPs P4
and refit as necessary