As long as your actuator has 5 pins do the test and see what happens.
Just posting here so you'll get an alert to see what I posted below.This must be driving you nuts. I reread reply #13 and you stated you had 4 wheel drive which would have been impossible to have without the actuator working no? All I can think of now is to connect the actuator to its harness,while not installed in axle, and observe for movement as an assistant pushes the 4High button - CAREFULL. If no movement then test for power at the harness leads, if power at leads , likely a new actuator is needed. No power would indicate a problem in wiring. Post back your findings when you can.