Set Appliance State:
| Isolate Mains Power to appliance as per TOPs P4 |
Set Multimeter to Resistance 
Disconnect connector X6 from the PCB
Measurement:
Check for continuity of the harness between the orange wires at the X6 connector marked 9 and 10 and the orange wires at the air pressure switch.
Visually inspect the harness for any signs of damage or wear.
Visually inspect the harness for any signs of damage or wear.
Isolate as per TOPs P4
and refit as necessary