Set Appliance State:
Set Multimeter to DC Volts 
Isolate Mains Power to appliance as per TOPs P4
Remove the main control box cover to expose the control PCB
Disconnect ribbon cable from connector marked CON 4 on the control PCB
Remove the main control box cover to expose the control PCB
Disconnect ribbon cable from connector marked CON 4 on the control PCB
| WARNING! - Mains voltage is expected during test follow TOPs P4 live testing procedure |
Measurement:
Measure voltage across pin 2 and pin 4 at CON 4 on the control PCB. Expected voltage 5 volts DC.
Isolate as per TOPs P4
and refit as necessary