Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Set Multimeter to Resistance Set meter to measure resistance
Disconnect ST17 connector from the right hand side of the PCB
Disconnect diverter valve connector
If available use the Worcester test PCB to assist resistance test

Measurement:

Check diverter valve harness for continuity of each wire in turn
at the PCB connector to the diverter valve connecter.
Red - Red
Orange - Orange
Blue - Blue
Yellow - Yellow
Green - Green
Black - Black
Visually inspect the lead for good general condition.