Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Set Multimeter to Resistance Set meter to measure resistance
Disconnect mains voltage plug from pump
Disconnect X1 from the PCB

Measurement:

Test 1.
Measure the resistance across pin 5 (Brown) and Earth (Main terminal block).
Expected resistance greater than 1MOhm (or O.L).
Test 2.
Measure the resistance across pin 6 (Blue) and Earth (Main terminal block).
Expected resistance greater than 1MOhm (or O.L).
Inspect harness and connectors
for good overall condition.