Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Set Multimeter to Resistance Set meter to measure resistance
Disconnect inline connector at pump for mains voltage

Measurement:

Test 1:
Measure between the brown and blue wires at the disconnected plug.
Resistance should be greater than 1 MOhm.
Test 2:
Measure between the brown wire and the earth wire at the disconnected plug.
Resistance should be greater than 1 MOhm.