99 f-350 4WD problem

[woodbutcher1953]

Hello, I've got a 1999 f-350 with approx 182K miles on it. I was trying to put it into 4WD the other day, and nothing. I checked the fuse and it was O.K., but I changed it anyway. When I use the shift-on-the-fly knob, nothing happens. I got out of the truck, and put the lock-outs in manually, and it still won't go into 4WD. I had the lock-outs re-built approx. 40k ago, along with the upper and lower ball joints. I am not mechanically inclined, so I have no idea if this is an electrical problem, or mechanical one. I hate to take it to Ford if it's something simple. Please help an old carpenter that is mechanically challanged. Thank you in advance. David

[Brian]

maybe the motor that flips the xfer case lever is kaput. just a guess!

[Karbo]

Maybe the pulse vacuum hub lock solinoid located on the firewall is bad. It's controled bu vacuum