Set Appliance State:
| Isolate Mains Power to appliance as per TOPs P4 |
Set Multimeter to DC Volts 
Lower front fascia panel
Gas On; Pilot On
| WARNING! - Mains voltage is expected during test follow TOPs P4 live testing procedure |
Measurement:
Measure the voltage at connector PL10 between the red wire (5) and the black wire (1) on the modulation control board.
Isolate as per TOPs P4
and refit as necessary