Set Appliance State:
| Isolate Mains Power to appliance as per TOPs P4 |
Set Multimeter to Resistance 
Disconnect plug from fan
Measurement:
Test 1:
Measure the resistance between pins 1 and 2 at the fan.
Resistance should be approximately 24.6kOhms.
Test 2:
Measure the resistance between pins 1, 2, 4 and 5 at the fan to a suitable earth point. (pin 3 does not need to be tested)
Resistance should be greater than 1M Ohm on each test.
Measure the resistance between pins 1 and 2 at the fan.
Resistance should be approximately 24.6kOhms.
Test 2:
Measure the resistance between pins 1, 2, 4 and 5 at the fan to a suitable earth point. (pin 3 does not need to be tested)
Resistance should be greater than 1M Ohm on each test.
Isolate as per TOPs P4
and refit as necessary