Set Appliance State:

Mains Power Off
Set Multimeter to AC Voltage Set meter to measure AC Volts
CH Demand
Mode Switch in LOW position
WARNING! Mains voltage is expected during test, follow TOPs P4 live testing procedure
Mains Power On

Measurement:

Measure Mains Voltage across the Red spaded wire and Blue spaded wire at the Gas Valve pilot Solenoid.