Set Appliance State:
Mains Power Off
Set Multimeter to AC Volts 
| WARNING! Mains voltage is expected during test, follow TOPs P4 live testing procedure |
Observation:
Apply heating demand.
After approximately 13 seconds voltage should be present at test points.
Measure the voltage across the purple leads on connector 4 on the PCB.
After approximately 13 seconds voltage should be present at test points.
Measure the voltage across the purple leads on connector 4 on the PCB.
Isolate as per TOPs P4
and refit as necessary