Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Set Multimeter to Resistance Set meter to measure resistance
Disconnect X13 from the PCB
Disconnect the lead from the diverter valve motor

Measurement:

Measure the resistance of each of the leads in the harness from the PCB to the diverter valve connector.
Expect Zero Resistance on each test
X13 pin 1 brown to brown @ diverter valve connector.
X13 pin 2 black to black @ diverter valve connector.
X13 pin 3 blue to blue @ diverter valve connector.