I have a 99 f150 4x4. The other day I put my truck in 4H and I thought it was in apparently it isnt. I always foot on brake then neutral than turn the *** on the dash. So heres the run down dash says the truck is in 4H and my front drive shaft is turning but my front wheels are not. The truck will not come out of 4H, it wont go to 2 or 4L. I would just like to get some ideas on what the problem is before I spend money on something that isnt the problem. I was thinking maybe my automatic lockers have went bad? Any info would be helpful. Thanks

 

are your cv axles turning as well? I know your wheels aren't but maybe somthing wrong with them or the vacuum hub.

 

Um im not sure I just had my buddy look at the front drive shaft as I moved the truck.

 

On a 99, you can not tell what the problem is with the vehicle is on the ground. The front axles/CV always turn, there are no hubs. All locking/unlocking at the front is done at the diff. So the front driveshaft will turn if the diff is locking. It will also turn if the transfer case is locking. You need to get it on a lift to really tell what is broke, diff/vacuum motor/solenoid or transfer case.
If you do a search for 4wd not working, you will find quite a few examples of the different problems found.

JMC has some good posts on the problems.

 

Ok kingfish thanks il look

 

My parent's '98 Expedition had the exact same problem. Turned out to be a vacuum problem.

 

Ok lets see if this helps anyone figure out my problem. So I get in the truck this morning to go to town. I back out of my gravel driveway onto the road when my front tires hit the pavement they start to bind and grab. Now my lockers suddenly have locked lol. I hadnt done anything to it just got in it this morning. So after the I realized the lockers were engaged I pull the truck back in the driveway. Put foot on brake put it in neutral turn the switch to 2wd, click click back to 2wd!!! 4x4 light off front drive shaft not turning. I didnt dare try to put it back in 4x4 cause I drive my truck 60 miles to work. Anyway if my lockers actually function does that mean I have a vacuum line problem like ncTidalWave said in earlier post? And if you all agree with me how do I go about finding a vacuum leak? Im a pretty decent mechanic but im lost on this one. Or any other things someone may think it could be?

 

Come on guys someones got to have something for me I have to figure this out!!

 

i have a 2001 with the same 4x4 system except i have a manuel shift on the floor but it seems to me that its a vacuum problem or a problem with the vacuum powerd front differential acutator sticking. But if the light on the dash is on that means the transfercase has engage like u said the front drive shaft is spinning so that verifys that the transfercase is engaged so i would check the solinoids behind the battery and then check for vacuum leaks and you might check to see if the front diff actuator is bad but i hope this helps. steven