Ford f250 four-wheel drive

[pig tracker]

I know this is nothing about racing but I don't know where to ask this question. I have a 2014 F250. Knob on dash to go from 2 wheel to 4 wheel drive. It seems to only work when it wants to. Ford House has not been any help. What actually activates the four wheel drive? When it works, I can hear a slight sliding of whatever locks it into 4 wheel drive. Do not hear anything when it does not go into 4 wheel drive. Is this activation achieved by electric, hydraulic, vacuum, or whatever? Anybody out there who can help? Thanks

[cumminsman08]

Does your 4x4hi indicator light come on every time you turn the knob on the dash?

[cumminsman08]

Try a little test for me, while in 2wd get in your truck turn your heater control to vent and fan speed on 4 verify air blowing out vents and not defrosters, then turn knob from 2wd to 4wd and see if you still have air blowing to your face.. if air switches to defrost (windshield ) then you have a vacuum leak or bad vacuum pump.. let me know what u find

[JHobbs26]

www.ford-trucks.com use that forum

[pig tracker]

Yes light comes on but in amber. That's when I took it to Ford and they said they fixed it. NOT. Sometimes it will not come out of 4 wheel drive. Other times it works fine.