Set Appliance State:

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

Measurement:

Test 1.
Measure the resistance between pin 1 (Live) and
pin 3 (Neutral) on the pump.
Test 2.
Measure the resistance between pin 1 (Live) and
pin 2 (Earth) on the pump.
Expect a resistance of greater than 1 MOhm for each test.
Note.
A reading of O.L is acceptable as this is greater than 1 MOhm.