Set Appliance State:
| Isolate Mains Power to appliance as per TOPs P4 |
Set Multimeter to Resistance 
Remove connector from pump and X1 from the PCB
Measurement:
Measure the resistance of each wire of the pump harness.
Note.
Earth wire from pump connector is measured to boiler chassis.
Expected resistance continuity (zero resistance).
Note.
Earth wire from pump connector is measured to boiler chassis.
Expected resistance continuity (zero resistance).
Isolate as per TOPs P4
and refit as necessary