Set Appliance State:

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

Measurement:

Measure the resistance of each of the wires in the diverter valve harness to check their continuity.
Expect zero resistance or continuity on each of the three wires.
Also inspect the harness visually.