Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Set Multimeter to Resistance Set meter to measure resistance
Remove connector CN4 from the main PCB
Remove the connector from the diverter valve

Measurement:

Measure the resistance between each of the pins on CN4 and the diverter valve connector as listed below:
Connector CN4Diverter valve Connector
Pin 1 (Black) Pin 1 (Black)
Pin 2 (Blue) Pin 2 (Blue)
Pin 3 (brown)Pin 3 (Brown)

Expect continuity on each test.
Also inspect the condition of the harness visually checking for any damaged insulation.
Note:
Each pin on the PCB connector is numbered.