No 4wd.

[axespino]

I have a 2002 F250 and the 4X4 will not engage. It has the switch inside and that does nothing. I was not able to manually lock the hubs a few months back but I am able to now but the 4X4 still not working. Awhile back I got a code when I accelerated pretty hard and got a code for overboost. I had the hypertech programmer installed at the time and cleared the code. The hoses going to the spindle appear to be on tight and the fuse to vacuum pump is good. Thanks

[owtcast]

Welcome to the board. There are a number of things that could possibly be wrong but they can be narrowed down a lot by checking if your front driveshaft turns when you select 4wd. Put it in 4wd and have someone check if the front driveshaft rotates while you ease forward. If it does then you have a problem with the hubs. If not, then the transfer case isn't engaging. Just a hunch but, if I had to guess, I would think the hubs were the culprit. They are notorious for having leaks on the seals. Also may want to check the lines going to them for any cracks.