Set Appliance State:
| Isolate Mains Power to appliance as per TOPs P4 |
Set Multimeter to Resistance 
Disconnect the wires from the water pressure switch
| Note Ensure that the system is pressurised before undertaking this test. |
Measurement:
Measure the resistance between the exposed terminals of the Water Pressure Switch.
Isolate as per TOPs P4
and refit as necessary