Set Appliance State:
| Isolate Mains Power to appliance as per TOPs P4 |
Set Multimeter to Resistance 
Remove the 4 wire connector from the fan
Remove connector X401 from the PCB
Remove connector X401 from the PCB
Measurement:
Measure the resistance of each of the 4 wires (brown, black, blue and green) from the fan connector to the corresponding wire on connector X401.
Expect continuity / zero resistance on each of the 4 wires in the harness.
Are the resistances measured as expected?
Expect continuity / zero resistance on each of the 4 wires in the harness.
Are the resistances measured as expected?
Isolate as per TOPs P4
and refit as necessary