2000 dodge cummins 2500, and just today I noticed that the 4wd isnt working. Just used it monday several times with no problems and now it wont work. I got to gas station and put it in 4wd (with truck running obviously) and pulled the vacuum lines at the t-case and no vacuum at all at any of the lines. One thing I did notice is a rubbed line that isnt connected to anything but while looking around (in the dark) there wasnt a line that it could connect to. There are 4 lines coming out of the top of the t-case, and 3 of them have lines they connect to, the 4th is a vent im guessing? Any help would be greatly appreciated.

Thanks a bunch!

 

check all of your vacuum lines. if there is a leak anywhere in the vacuum system it causes the whole thing to fail.

this includes vent control and cruise control.