Set Appliance State:

Mains Power Off
Gas On; Pilot On
Set Multimeter to AC Volts Set meter to measure AC Volts
Selector Switch OFF
Gas Control Knob in Main Burner position
WARNING! Mains voltage is expected during test, follow TOPs P4 live testing procedure
Mains Power On

Measurement:

After 30 seconds of operation measure the slow fan voltage across connections 4 (Fan L, red wire) and connection 3
(Fan N, purple wire) on connector CN2.
This should be in the range 160-180 Volts AC.