Front differential will not lock in? Transfer case shifter moves but actuator does not inguage. Any suggestions where and what to look for?

 

I don't have a clue, but I have seen repeated posts saying to pull the front cover and lube everything up. If you have vacuum it might just be something stuck. Also, if you search the forum there are a bunch of other posts. The one below seemed pretty helpful.
https://www.ford-trucks.com/forums/7...t-working.html

Good luck.

 

There is a vacuum actuated motor on the front of the diff. It's under the plastic cover that mjuk1 mentioned. Check the vacuum hoses going to it, and make sure the lever isn't jammed up with "gunk".

 

Do as the other guys have said. I removed mine the other day to diagnose the same thing. Remove the plastic cover with the three 10mm bolts so you can see what is going on. If you don't have a vacuum pump, I just bought one to diagnose this and an EGR valve problem. It has already paid for itself. I just hooked the hose up to each port on the actuator that moves the arm on the axle. It worked fine hooked to the pump. I followed the vacuum hoses up and discovered I had a crack at one of the fittings. Easy fix. Originally, my actuator seemed stiff so I used some PB Blaster and ran it in and out with a small prybar and it seemed to free it up. Hope this helps.