i got a 2006 f250 with the powerstroke in it and i got no 4 wheel drive on the dash the light comes on but it dont engage even if i got out and lock the hubs it still dont work and help would be great thanks
If the light is on, that means the transfer case actually shifted into 4x4.
With the switch in 4x4, and the light ON, jack up the front wheels off the ground and spin each one. See if the u-joint behind the wheel spins with the wheel. It sounds like one of your hubs is hanging up and not really locking.
It may be worth taking the shift motor off of the transfer case and inspecting it also.
I believe it is possible for the motor to break in such a way that it still moves the switches but doesn't actually turn the shift cam shaft. The switches are what reports back to the 4WD control modules that the shift has completed.