Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Set Multimeter to Resistance Set meter to measure resistance
Remove connector CN10 from the PCB
Remove connector from pressure switch

Measurement:

Measure the resistance between the pins on connector CN10 and the pressure switch connector as per the table below.
Connector CN10Pressure switch connector
Pin 1 (Black)Black
Pin 2 (White) White
Pin 3 (Red)Red

Expect continuity on each test.
Also visually inspect the harness visually for general condition and any damaged insulation.