Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Set Multimeter to Resistance Set meter to measure resistance
Disconnect connector J2 from the ignition PCB
Disconnect wires from fan

Measurement:

Inspect the condition of the harness between the fan and the PCB.
Check for continuity (zero resistance) between the ends
of the two wires running from the PCB to the fan.