I have a 1998 F-150 4X4. This truck has the elecrtronic switch on the dash to the right of the steering wheel. When I move the switch to 4X4 high or 4X4 low it sounds and feels like the transfer case is engaging, but the front wheels are not pulling. Please give me some hints where to start trouble shooting.
Thanks,
tonymac15

 

Do you have locking front hubs? If so your problem may be there. If you do have locking front hubs are they auto or manual? The auto hubs can be unreliable.
You can check the front hubs by putting the transfer case in 2wd, lock the hubs (if manual), get under the truck and turn the front driveshaft by hand. It should not turn. If it does then one or both of the locking hubs is bad.
You might get a better response to this if you posted in the `97 F-Series page.
Good luck.

 

The style of front axle you have does not have lock outs on each front wheel like older trucks. It has CV axles which are solidly splined to each hub. The left axle goes directly into the front differential, while the right axle is splined to a disconnect system. There is a shift fork that is actuated by engine vacuum when you engage 4x4. There are little plastic "fingers" on the fork that tend to break, and will no longer engage/disengage the right hand axle from the front differential. That is where I would look first.