Set Appliance State:
| Isolate Mains Power to appliance as per TOPs P4 |
Set Multimeter to DC Volts 
Disconnect the in-line connector to the Aqua Sensor and make safe
| WARNING! - Mains voltage is expected during test follow TOPs P4 live testing procedure |
Measurement:
Measure the DC voltage between pin 13 on connector X2 and a suitable earth point.
Expect approximately 4.7 Vdc.
Is the voltage measured as expected?
Expect approximately 4.7 Vdc.
Is the voltage measured as expected?
Isolate as per TOPs P4
and refit as necessary