Set Appliance State:
| Isolate Mains Power to appliance as per TOPs P4 |
Set Multimeter to DC Volts 
Remove the interface harness plug from X51 of the PCB
| WARNING! - Mains voltage is expected during test follow TOPs P4 live testing procedure |
Measurement:
Measure the voltage between each of the 6 pins on X51 to a suitable earth point.
Voltages should be approximately as below:
Voltages should be approximately as below:
| Test Point | Voltage (DC) |
| Pin 1 | 0 |
| Pin 2 | 5 |
| Pin 3 | 0 |
| Pin 4 | 5 |
| Pin 5 | 22 |
| Pin 6 | 5 |
Isolate as per TOPs P4
and refit as necessary