Ok so i will probably get some of the acuall names wrong but here goes. Las t winter 4x4 quit working. Replaced vacume acuator on firewall worked for a short while. Now the acuators on the wheel engage when vacume is removed correct? So unpluged vacume lines at firewall still nothing. Well I wasn't sure how it worked so took it to two diffrent shops and got 2 diffrent problems. Spring came and didn't worry about it anymore. Now I had it on a drive on lift the other day and I couldn't turn the pass cv axle but could turn the DR side. So since no vacume since truck wasn't running the Dr side acuator is bad correct?

 

It could be more than that. The default setting of these actuators is 4x4 so with no vacuum it should be engaged. Being that it was not engaged I would think that the spring inside the actuator is bad. Take it apart and clean everything out. Do not stuff it full of grease like a manual hub, just a little grease is sufficient. Those things are $110 a piece, I have already changed mine.......Hate the actuators...Good Luck...