Today I got the urge to work on my non-functioning CAD. The CAD vacuum motor gets no vacuum in either 2 or 4wd.
I removed the vacuum switch on top the transfer case. (it wasn't as hard to get to as I feared). It seems to work. It is a 2 way valve with 4 ports. The ports cross when you push the little ball at the bottom. The switch holds a vacuum, and doesn't cross a vacuum to the ports that it shouldn't cross to. The switch seems to work just fine
I have a strong vacuum from the vacuum source when the truck is running.
The red and black vacuum lines leading from the switch to the CAD vacuum motor hold a vacuum when I test them. No leaks. Every individual part seems to work and be in good shape.
But when I connect it all up still I don't get a vacuum to either the red or black lines going to the CAD motor. I am puzzled.
I suspected that the soft rubber line connections on top the switch must leak. I checked it carefully and can't find any cracks. I still suspect that it may not hold a seal against the connections on the switch. Can you buy that rubber 4 holed connector? Anybody got any other suggestions, other than buying an electrical solenoid to put on the CAD?.
Tom

 

Maybe the vacuum lines were disconnected before you got the truck and insects have plugged them up.

 

i took my rubber gromet off and just pulled the hose out one by one and put small vacum line on them then stuck them back where they went individualy and i got vacum then but it still didnt fix my prob i finally bought the manual actuater from summit 4x4 posi lock i think is the company thats the best money i spent on my drivetrain so far it is awsome

 

I checked it out again. Every thing looks fine and there are no obvious problems, Nothing is plugged or leaks; the switch works, plenty of vacuum to the switch. It is just when I plug the soft rubber 4 way block into the switch, the vacuum doesn't go through. I hate to have to spend $200 for a mechanical cable system when the problem is seemingly so simple.
On the other hand, I sure can't argue that a vacuum activated disconnect in general is anything other than a piece of crap. Even if I get it working, it will likely fail again, and most likely a very inopportune time. I guess I had better get my wallet out.

 

i made my own posi-lock on my jeep for about 20 bucks. i tapped the side of the CAD and threaded in a long cable (for a bicycle for two brake) and put a spring on the other side. then just rigged up a lever inside. it hasn't let me down in over two years, and its constantly getting engaged and disengaged bc its the only way i can turn (spooled in the front )

 

Cougsfan, what did you ever do on your CAD issue? I just found mine is having the same problem. I tracked down the problem to a vacuum leak in the 4-way rubber connector. The rubber just won't seal on the switch anymore.
Trying to find that connector now.

Chris

 

I looked at it very close again for leaks and never did find the problem. So after I got stuck in our pasture and had to spend a couple hours getting the truck out, I figured enough was enough. I bit the bullet and bought an Posi-lock. It went on fairly easy, and now, for the first time since I owned the truck, the 4wd works.
I too suspected the 4 way rubber connector, It seemingly was the only thing left that could be bad! So inspected and tested, reinspected and re-tested it, never finding anything that even remotely indicated a problem with that 4 way connector. Kind of embarrassed me to myself and ticked at myself for giving up. It should be an easy problem to deduce and isolate. But it wasn't.
One other thing occurred to me that might be the problem; maybe whatever pushes the vacuum switch in and out inside the transfer case is stuck half way?? With hind sight, maybe I should have felt inside the hole for the vacuum switch with the lever in and out of 4wd.

 

Got the 4 hose connect grommet from the dealer, for about 7 bucks. That fixed it.

Chris