Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Set Multimeter to Resistance Set meter to measure resistance
Gain access to pump electrical connections at pump
Remove the wires from the pump electrical connections

Measurement:

Test 1.
Measure for resistance across live & neutral terminals of the pump.
Expected resistance 160 Ohms or greater.
Test 2.
Measure for resistance across live & earth terminals of the pump.
Expected resistance greater than 1Mohm.
Note.
1. Ensure a good connection is made or misdiagnosis will occur.
2. Resistances may register as O.L on the multimeter, this would indicate a resistance greater than 1Mohm.