03 F250 4x4 not

[noneck]

Ok...know I have some work to do...but hoping someone can help narrow my workscope? My 4x4 hubs are not Auto engaging, nor can I turn the manual engage. Anyone else played in this area? I do have shop manuals and will be digging in likely after a near "stuck" event as its too cold to be sitting outside working on something I consider a convenience.
What I do know is...
4x4 engaged spins the front drive line and the axle (son has observed).
2003 4x4 hubs are combo...Auto and Manual
2003 4x4 hubs Auto actuator is vacuum operated
Just looking to narrow the effort and gain some focus for this old garage mechanic, Thanks

[ldunning]

When I had a problem with the front hubs not locking in it was a seal in the hub that was bleeding off the vacuum and thus there was not enough vacuum to engage the hubs. I was able to lock the front hubs manually. You can check vacuum at the hubs by disconnecting the vacuum line at the hubs. There is a vacuum pump and I believe a relay under the hood mounted on the right inner fender. Good Luck

[ronstan]

Since they are vacuum operated I would check to see if you have a leak somewhere. I seem to remember on a ford forum that that happened to a guy.

[noneck]

Ok, ldunning do you do anything special to manually lock the hubs? I tried to turn the locks but seems I'm a weakling...?

[ldunning]

I could turn the bar with my fingers. No problem, just like the old Warn hubs. I had moved the locks every year or so and I haven't been in that wonderful NY winter weather. If you are able to get the switch to rotate you might want to pull the fuse for the vacuum pump or disconnect it since it would run continously whenever the dash switch is in 4x4 and the ignition is on.

[PowellsMonty]

Sometimes I had to rock the truck back & forth while trying to turn the bar on the wheel to free it.