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.
Expect Zero Resistance on each test
Red to Red(R)
Black to Black(B)
White to White(W)