I know there are thousands of threads out there concerning 4wd that will not engage, but I've only found one (which wasn't very helpful) regarding 4wd that won't disengage. The problem happens about a quarter of the time I use 4wd. When I put it back in 2hi the dash light turns off, but I'm still in 4wd. There is binding in the driveline and it's obvious that it is still engaged. I have MSOF.

 

Mine does it too, I just back up a little and it pop's right out.

 

First you should not need to back up to get it out of 4wd. If you have to it has a problem.
The problem of getting out of 4wd, can be very near the problem with getting it into 4wd. For one, there are 2 solenoids on the firewall for locking and unlocking the front diff. One locks it and the other unlocks. They each have a vacuum line to the vacuum motor on the diff. If the unlock solenoid is intermittent or the vacuum line is cracked, you could have th problem of not getting it out of 4wd.

 

Alright well I'll go check the vaccuum lines today. As far as an intermittent solenoid, what should I do to diagnose that? Just wait until it happens again and then check the solenoid or is there another way? I don't think it's a shift fork problem because it engages perfectly, but is it a possibility?

 

I to had the same problem. We had 12 inches of snow in NY and my 4x4 would not engage. Once again this site is the best. Did some research on threads and pieced a bunch of info together. Of course I was under the truck in a blizzard because I could not handle that my wifes 4runner pulled me up hill in 12" of snow over 100 yards to get my truck out of my neighbors driveway. Enough babbling. I located the diaphram under the front diff. There are two vacuum lines that run to the diaphram. You can either remove the plastic shroud or just pull it back. Behind is an arm and piston that activates the 4x4. I was able to push and pull with a screwdriver the arm and this seems to engage and disengage the 4x4. Now it seems to work ok. I think it might have been from hosing the under side of the truck because of road salt. Seems to be a bad design. I called ford to check for recalls. NO LUCK. They said they are aware of the problem but "It's my problem!"

 

I would guess it could be sticking, though I doubt if it is broke. As for testing the solenoid, you mike hook it up to a vacuum gauge and go back a forth on 2wd to 4wd. Do it on both solenoids and make sure your are getting the same amount of vacuum.