i got a 95 12 valve and the 4x4 is not engaging to the front axle. i pulled all the vacuum lines off and they are good no leaks. the red and green line do not have a suction to them idk which one is supposed to get the suction but both aint.Like i said though the rear end is locking and so does the front driveshaft

 

Maybe this will help.

Central Axle Disconnect (CAD) System Troubleshooting

 

its more than likely the tcase switch, when you engage the lever it turns on the vacum to the cad, if its bad it wont work.

 

yep, posi lock cable is a cheep, easy, and good fix

 

I have it an it's really nice to have. Just one less thing to worry about

 

I'd look into the cable, if I were you. Vacuum for lock was a bad idea on Dodge's part to begin with, if you ask me. Vacuum fluctuates, which means the it's possible that the lock will fluctuate in and out as well, when bumping the accelerator.

 

If you are not getting any vacuum you may have a cut line or your switch on top of the transfer case is stuck. Check you lines were they run up beside the front drive shaft thats were mine were rubbed into. I fixed it with a small piece of rubber line that slides over those lines and put some tape on them to keep them from being pulled off. I would go with the cabl lock also if it was going to cost very much money to fix. It is probably a cut line somewhere thought.

 

ok i got vacuum to the t case and if i take the main vac from the motor and hook it to the black vac line to the 4x4 then i got 4x4 and jus switch lines when i want 2 wheel drive. its somethin in the t case and i cant figure it out

 

that would work only problem is its just a pain to have to keep doing that.

 

buy a vacuum switch and hook it to a toggle in the cab thats what i did flip the switch to lock the hubs