Set Appliance State:
Gas On; Pilot On
Set Multimeter to DC Volts 
CH Demand
Isolate Mains Power to appliance as per TOPs P4
Selector Switch Summer position
Link pins (1) and (2) of five pole connector on mounting frame
Selector Switch Summer position
Link pins (1) and (2) of five pole connector on mounting frame
| WARNING! Mains voltage is expected during test, follow TOPs P4 live testing procedure |
Measurement:
Measure DC voltage across connector CN4 connections 9 (Blue) and 8 (Grey).
The negative probe goes on connection 9 and the positive on connection 8.
Voltage should be less than 0.5 Volts DC.
Remove link.
The negative probe goes on connection 9 and the positive on connection 8.
Voltage should be less than 0.5 Volts DC.
Remove link.
Isolate as per TOPs P4
and refit as necessary