I recently purchased a 2001 F250 4x4 only to find out very recently that the 4wd isnt working. I test drove this truck before purchase and everything "appeared" to be ok. Trouble began this past weekend when we went to put the truck into 4wd and got no lights on the instrument panel. after doing some tracing i found that the electrical connector to the transfer case was not fully plugged in and as soon as i plugged it in and retried it i was able to get a fully functional instrument panel. The problem is that the truck is still not working in 4wd no matter whether i put it into 4 wheel high or 4 low (and yes i did change the hubs from auto to lock). I can see that front driveshaft turning but the front wheels will not turn. Found this one out the hard way by going down a sandy road and all but burying the truck. I hear the transfer case clicking in and watched the front driveshaft turning while i had someone else driving but just no pull outta the front wheels. Any ideas on what may be the cause of the problem?

 

Vacuum leak maybe causing the hubs to not fully lock, or could be bad hubs


Strokin' Away

 

Im new to the shift on the fly 4wd but isn't 4 high controlled by the vacuum and 4 low controlled by the hubs being locked? I just don't wanna throw parts at a problem but to me it sounds like hubs would bethe common element and more likely to be the problem????

 

Its all controlled by vacuum.when you turn your air on does it only come out of the defrost vents? If so it's a vacuum leak somewhere in the system.


Strokin' Away

 

A/c works fine and switches between all vents properly

 

Sounds like hubs then.but can't be 100% sure.pop your lug nut covers off and you'll see a snap ring pull those off and your hub pops right off, look for any broken gears or out of place pieces, then look at your hub and lock it in and out if you see no changing of gears moving then Id say hubs but you'll want to get a new rubber o ring and clip before you take them off. Riffraff or guzzles diesel o rings carries them.


Strokin' Away

 

well after tinkering around this weekend i found that when it is in 4wd the air does switch to blowing just out of the defrost vents. it looks like i am about to begin the hunt for a vacuum leak.

 

Vacuum leak aside, you can still manually turn the hubs and that should lock the hubs regardless. The hubs are dual purpose, either auto lock (vacuum) or manual lock (get your butt out and turn them by hand) so if you turn them by hand and still don't have 4x4, it's more than a vacuum leak bud...

manual or auto can be used for 4 high and 4 low. Not one for the other. Both work on both settings.

 

come to find out it was bad vacuum lines on back side of wheels. replaced and problem was solved. thanks for the help.