I have a 1999 F250 3/4 ton gas engine 4x4 with 110,000 miles on it. The truck as the switch inside the cab to put it into four wheel drive and although 4 high and 4 low light up in the dash I have no four wheel drive. After reading several posts I decided to change the actuator as it appeared to be locking up. After the change I put it into 4x4 and now I have the two back wheels turning and the front right wheel turning. When I take it out of 4x4 those 3 wheels are still turning. There is a red and a blue hose going to the actuator. The red hose has vacuum but the blue hose does not. Should there be vacuum at the blue hose or do I have a leak somewhere and what would be causing the right wheel on the front to be turning? Thanks

 

drop the automatic push button crap and but manual t-case and hubs...problem solved...tracing issues through that junk can be a major pain, not worth it IMO, manual stuff is ten billion Xs more reliable and about the same amount easier to fix, plus the parts are bigger...bigger=stronger and probably cheaper to replace too

 

How did you determine which wheels were spinning? Unless you have a limited slip or locker in your front axle (no factory trucks came with that) then only one wheel will turn per axle. If this is a superduty you will have a manual backup hubs that can be turned to "lock" incase of a vacuum failure. Try locking in your hubs and if it operates properly at that point you will know you have a vacuum problem. Hope this helps.

 

I had the truck sitting up on blocks. The four wheel drive engages fine other than the fact that the front left wheel does not turn. Another problem is that when I disengage it nothing happens those 3 wheels keep on turning. I have to actually shut the truck off in order for it to disengage. Could this possibly be the transfer case motor or something electrical? But that wouldn't make sense to me why the front left wheel won't turn. As far as i know it has automatic hubs on there is it still possible to turn these? What would it take to put the manual hubs on there because i really don't mind getting out to turn them. by the way its not a superduty.

 

Is it the light duty F250? (The 97-03 F150 body style???) If so it doesn't have hubs, it has a vacuum operated disconnect in the differential and drive flanges.

The open differential in the front explains why only one wheel in the front turns. Put it down on the ground put it in 4wd and make a real sharp turn. If it starts jerking around then you know your 4wd is working.

 

yes it is the same body style as the F150 and is light duty F250. I will try that and see what i get. Thanks

 

Ok well then you don't have hubs they're basically drive flanges, so if one wheel is turning the center disconnect is working. The only other possible problem would be a broken half shaft or cv joint on the side that isn't spinning. While the truck is off and not in 4wd see if you can reach up and turn the half shaft by hand that is going to the tire that isn't turning.

I'd try the driving and turning method first though - I don't think you have anything wrong.