Did you ever figure out what was wrong? I am having the same problem!

 

Is the front axle disengaging? (lite goes out) Or is the T-case dropping out of 4x4?

 

light goes out while driving so 4x4 disengages then light comes back on and 4x4 reengages.
I’ve replaced vacuum pump and vacuum lines . I’m getting 25 - 35 hg at the actuator

 

Did you replace the metal lines as well? Mine rusted out......

You are getting REALLY good vacuum though, can you monitor it while the problem is actually happening?

 

Pull the actuator off slide the fork over and permanently lock it in place.

 

I pulled all my vacuum actuator stuff out on my 1996 Ram 1500 and put in a perm-lok, and have never looked back.

http://www.alloyusa.com/permanent-di...am-pickup.html ($60.00)

http://4x4posi-lok.com/app_dodge.html (part #1100).

I also replaced the shift fork. Check this out below - I go into a little more detail:

https://dodgeforum.com/forum/2nd-gen...ml#post3162272

 

Mine the rubber fitting on the end where it goes on to the cad let water into it and rusted up the inside of the tube. No vac was getting to the cad, If this happened you may not be completely blocked but not getting enough vac to keep the cad in position. If you are getting the wild vents the vac is dropping out witch wont help. You may be showing good vac at idle but when accelerating it will drop out. You may want to replace the check valves on the vac lines.

 

On my 96, The vacuum fitting at the axle would allow moisture into the lines, and it froze........ so, when I yanked back on the expensive stick, nothing happened...... Had to park the truck in the garage, point the jet-engine heater under the truck, let it run for a while, then blow out the lines....... I used zip ties to get the vacuum fitting to seal better.

 

They stopped that two-piece axle cr@p on the Jeep XJs, ZJs, and TJs; but I don't know why at the same time they continued it on the Gen 2 Ram 4x4s. Minimal (if any) improvement in MPG with the two-piece axle design. If there was an improvement in MPG, don't you think Jeep would have kept the CAD in those models?

At best, it works "ok" when everything is working right, but there are too many parts to the CAD system - in that if any part stops working, the whole thing doesn't work. Even when mine was working right, there would still be a slight delay from when I pulled the lever to when the 4x4 light came on (especially if I hadn't used 4WD in a while). And sometimes that delay time (even if just a few seconds) was critical.

I'm telling you - get the perm-lok (see post #16 above). No more getting stuck because you can't get the front axle to engage. No more laying in the snow trying to find out where your vacuum leak is. No more tracing vacuum lines for cracks/leaks. No more heating-up your frozen lines and then trying to blow them clear to get your 4WD to work. No cables to pull (like the similar but more expensive and complicated posi-lok). And probably most important, no more wondering if it'll engage when you really need it.

https://www.summitracing.com/parts/pos-400/overview/ (the more complicated and expensive Posi-lok - if you really feel the need to have your front axle shaft separated at times)

https://www.summitracing.com/parts/pos-1100/overview/ (the one you want - the cheaper and simpler Perm-lok)

http://www.alloyusa.com/permanent-di...am-pickup.html (an even cheaper place to get the Perm-lok)

And I'm running a true-trac in the front axle - even with the perm-lok you don't even know it (true-trac) is there in 2WD.

 

I have the posi-lok 1100 in my truck. The axle shafts are splined to the hubs and turn all the time anyway. I think it's the best fix short of buying a free spin kit.