Set Appliance State:

Set Multimeter to Resistance Set meter to measure resistance
Isolate Mains Power to appliance as per TOPs P4
Remove connector CN4 from the PCB.
Remove connector from the fan.

Measurement:

Measure the resistance of each of the wires in the fan harness from connector CN4 to the corresponding wire on the pump connector
Expect continuity on each of the wires in the harness.
Also visually inspect the harness.