Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Set Multimeter to Resistance Set meter to measure resistance
Remove the 4 wire connector from the fan

Measurement:

Test 1:
Measure the resistance between the following pins:
The resistance should conform approx. to the table below:
PinsResistance
2 and 518.8kOhms
4 and 5 14.9kOhms
2 and 433.7kOhms

Test 2:
Measure the resistance from each pin on the fan to earth in turn.
Expect a resistance on 1 MOhm or greater on each test.
Note:
This test is carried out with the fan in place.