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)
Remove the gas valve connectors from the gas valve and make safe
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Measurement:

Reset appliance if necessary (press and hold reset button for 5 seconds, then release).
Test 1:
Allow ignition sequence to commence and measure the DC voltage between pin 1 on connector ST9 and the DC Neutral terminal.
Approximately 27 vdc should be present which reduces to approximately 0 vdc during the sparking stage of the ignition sequence before returning to approximately 27 vdc when sparking ceases.
Test 2:
Repeat above test for pin 3 of ST9 - the voltage should behave in the same way.
Notes:
1. Ensure a good connection is made and take care not to short the connections.
2. Lockout will occur after 5 attempts to ignite, reset as required until tests are complete.