Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Set Multimeter to Resistance Set meter to measure resistance
Slide connection PCB out and remove connector X3
Lower control panel to gain access to the programmer / timer connector situated on the reverse

Measurement:

Measure the resistance between each of
the wires in the harness in turn.
Blue to blue
Grey to grey
Black to black
Brown to brown
Expect continuity / zero resistance on each of the wires.
Also visually inspect the condition of the harness.