Set Appliance State:

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

Measurement:

Observe the position of the spindle.
If the spindle is extended test between pins 2 and 3.
Expect approximately 9 Kohms.
If the spindle is retracted test between pins 1 and 2.
Expect approximately 9 Kohms.
If the spindle is not fully in one position test between pins 1 & 2 then pins 2 & 3.
Expect approximately 9 Kohms.
Note:
Pin numbers are printed or stamped on the diverter valve head itself.