2000 F250, 7.3 Diesel, Automatic Trans, 4x4, ESOF

Shifts into 4-Hi just fine, however, when I then go to shift into 4-Lo (in neutral, stopped, foot on brake), transfer case engages & 'low range' dash lamp lights...then 1-2 seconds later, transfer case UNengages, light goes out (still in neutral)...maybe 1-4 seconds later it re-engages (light also comes back on), then disengages, etc., and the cycle continues, all while in neutral. I am able to shift into Drive (when it's engaged & light is on), and it does go into 4-Lo, although I'm not sure if it will remain in 4-Lo continuously while driving.

Other info: the auto hubs are in Auto position, and are somewhat difficult to turn. With the hubs in this position (engine off), I am able to turn each u-joint by hand at each wheel. When starting, vacuum pump seems to run for about a minute. A/C vents properly from front vents, and does not revert to defrost mode when engaging 4wd.

I appreciate any guidance you can give me on this. Go easy on me, as I have almost zero experience in working with these kinds of things!

 

You're following the right procedure for getting it into 4LO, so you can check that one off the list. I don't know a lot about the motor that switches the case, but it sounds like it may not be the culprit. It's switching in, but just not staying. It may be a problem inside the case itself.

The hubs won't have anything to do with the transfer case. It's correct to be able to turn the u-joints by hand when the engine is off and they're in the Auto position. In the auto position, they won't engage until the vaccum pump is running and the 4x4 switch is engaged.

 

If you shut it off in 4x the hubs will (should) remain locked untill you switch it to 2x with the key on and vacuum present in the resivior. The system only uses vacuum to engage or disengage, not to hold them engaged.

 

Thanks for the responses. I appreciate your help. Now I'm getting concerned...

New symptoms showed up today, in addition to the above. From a standing stop (pavement), selected 4x4 Hi, engaged fine. As I moved forward, I began to hear a high pitched squeal or whine. Squeal didn't change when braking. A/C blew out correct vents. After 2-300 yards, switched back in to 2wd. Squeal continued. Pulled into a parking lot, could feel front wheels still engaged. Checked front u-joints & could not turn them by hand, even though I should have now been in 2wd. Reversed 50-60 ft, shifted to Drive and squeal went away. Checked u-joints again, they now would turn by hand although they were significantly stiffer than when checked a week ago, and...each one squealed when turned by hand. Very similar to the squeal heard on the road.

I'm I headed for a high dollar repair on this? Am I ok to drive in 2wd until I can get it fixed? I'm north of Seattle & don't even have a clue who I should have look at this, other than the dealer. If it's relatively simple, like maybe cleaning/lubing the auto-lock hubs, I may be able to give it a shot. Other than that, I don't know that I should attempt to fix 'er myself.

I appreciate your guidance on this one.

 

I suggest a good set of WARN premium hubs and plug off the vacuum ports at the knuck and at the fender well. Inside the fender well you will see three black hoses. One is the ABS the other is a brake line and the other is the vacuum line that engages the "auto" hubs. Take that cheesie vacuum line off. Plug both ports it was connected to with some good rubber vacuum caps and replace the OEM auto/lock hubs with the WARNS.

Hope this helps