Set Appliance State:
| Isolate Mains Power to appliance as per TOPs P4 |
Set Multimeter to AC Voltage 
Control Thermostat in high position
High/Low Switch in High position
High/Low Switch in High position
| WARNING! Mains voltage is expected during test, follow TOPs P4 live testing procedure |
Measurement:
Allow the Boiler to purge itself and the Burner to ignite.
Measure the voltage across connection 1 (Brown wire) and connection 2 (Blue wire) on the connector identified as GV2 on the Interconnection Board.
Measure the voltage across connection 1 (Brown wire) and connection 2 (Blue wire) on the connector identified as GV2 on the Interconnection Board.
Isolate as per TOPs P4
and refit as necessary