Set Appliance State:
Mains Power Off
Gas Off
Set Multimeter to AC Voltage 
CH Demand
Purge Switch in NORMAL position
HW Switch in OFF position
CH Switch in CH Continuous position
CH Potentiometer set to maximum
HW Switch in OFF position
CH Switch in CH Continuous position
CH Potentiometer set to maximum
| WARNING! Mains voltage is expected during test, follow TOPs P4 live testing procedure |
Measurement:
Allow the Fan to operate.
Measure the Voltage across the Red wire and the Blue wire on the Pilot Solenoid.
Measure the Voltage across the Red wire and the Blue wire on the Pilot Solenoid.
Isolate as per TOPs P4
and refit as necessary