Ok. The 4x4 works sometimes and not other times. The light rarely comes on when in 4x4. To start things off I was out driving in some snow this winter in 4x4(or at least the lever was in 4x4) and I was going up a small hill and all of a sudden the 4x4 quit working. I never heard any grinding or anything. 4x4 hi and 4x4 lo was both the same. I moved the lever from Hi to Lo several time and then It started working. So I figured the linkage was out of adjustment. So next day I adjusted it and it seemed to work although the light was not on. Couple weeks later I ran into some mud and got it stuck. Turns out the 4x4 still was not working right. After moving the lever from hi to lo several time it finually worked and still there was not light. I backed it up out of the mud and stoped and put truck in Park. Got out to get something and got back in and put it in reverse and I was in a little wet grass and and the 4x4 quit working so I was just spinning. I have heard alot of people say "Oh you have a vacuum line leak". But they say if it leaks then your cruise control will not work. But my cruise control work great, no problem. Any ideas on what is wrong and how I can fix it.

I could be wrong. However I believe that the 2001 trucks had electronic cruise control, as do I believe my 2000 has. The vacuum system should still control the CAD unit and I think the heater vents. This could be a problem with it. I know on the Dakotas the actuator? on the axle routinely goes when they get older. However vacuum is very easy. Drop $10-$20 for a vacuum gauge you will probably use it again as they can be helpful with a ton of things. With a little vacuum hose and possibly a t-fitting you can easily test what the vacuum is doing at specific places in the system.

  cummins2k said:

I could be wrong. However I believe that the 2001 trucks had electronic cruise control, as do I believe my 2000 has. The vacuum system should still control the CAD unit and I think the heater vents. This could be a problem with it. I know on the Dakotas the actuator? on the axle routinely goes when they get older. However vacuum is very easy. Drop $10-$20 for a vacuum gauge you will probably use it again as they can be helpful with a ton of things. With a little vacuum hose and possibly a t-fitting you can easily test what the vacuum is doing at specific places in the system.

Where would I start? What else does the vacuume control? Could my hubs possibly going out. Do I just get a regular vacuume gauge like what you would put in the cab or are there a different one? I would probually just get it at an auto store right??

Basically on a Dodge diesel is the HVAC system and the CAD axle control. (98.5 to 01) From (01.5 to 02) the only thing vacuum controls is the HVAC. The only optional accessory is exhaust brake which is vacuum driven. Like said above just use a test vacuum gauge and test you line under the truck checking source and switching abiliites of the 4WD vacuum switch.

If you have vacuum then use a vacuum tester and make sure the diaphram in the cad isn't blown or cracked. I have seen the sliding collar break and the shift collar has wear strips that can fall off and it will not move the collar far enough to engauge also. just some other things to check. Remeber the cad only has 4 bolts holding it on and only takes a couple minutes to remove to inspect it.

wild when you remove the CADwill it leak much gear oil ? IF so do you need to top up in the front diff ?? Also - if it needs replacing - anywhere know where to get the part ?? Was thinking about a posi-lok.:P

Will have to go to town to get a vacuume gauge. What should the gauge read if the vacuume pressure is good. Could I replace the hubs with manual lock outs for this truck? Would they be a good idea or should I keep the auto locking hubs? Thanks for all the help.

  Cummins2001 said:

Will have to go to town to get a vacuume gauge. What should the gauge read if the vacuume pressure is good. Could I replace the hubs with manual lock outs for this truck? Would they be a good idea or should I keep the auto locking hubs? Thanks for all the help.

It will not leak much oil out at all if any. It should be around 20+ inches of vacuum. To test the CAD diaphram itself you will need a vacuum test pump. Can get them at any auto parts or tool shop pretty cheap. Below is just to give you an idea of what it is. You can get less fancy non brake bleeder testers as well. http://www.sears.com/shc/s/p_10153_12605_00920930000P?vName=Tool%20Catalog&cName=AutoSpecialtyTools&sName=Auto%20Hand%20Tools&psid=FROOGLE01&sid=IDx20070921x00003a Our rigs do not have auto locking hubs. They are live axles with a center disconnect on the passenger axle. If you can justify the 1200-1500 dollar cost of the manual locking hub conversion they are not a bad idea.

I have never heard of a CAD. What is it?

---------- Post added at 07:56 PM ---------- Previous post was at 07:46 PM ----------

Never mind I figured it out( Central Axle Disconnect:smart:)

---------- Post added 04-19-2010 at 06:46 PM ---------- Previous post was 04-18-2010 at 07:56 PM ----------

I was thinking I would just replace that stupid Vacuume activator with the posi lok. Posi Lok would do the same thing as the vacuume activator does right. I thing the posi lok would be WAY more reliable than the what on there. Any Suggestions or good points?

Then you can remove all the vacuum piping from the axle back to the t-case. if you don't mind having a big cable handle running into the cab.

Do you pull on a cable or twist the handle?

I have not seen one in person but I believe it is a pull type cable.

Ok Thanks. I think I am going to get the posi-lok instead of screwin around with the vacuume lines. After my bank account has the money of course.

  Wild and Free said:

Then you can remove all the vacuum piping from the axle back to the t-case. if you don't mind having a big cable handle running into the cab.

I heard of these too that replace the vacuum motor with a pull cable.. This way you could actually get 2WD LO range...

Good point Mike I forgot to mention that also.

Here is a used posilock system for sale if you are interested. http://www.midwestdieselconnection.com/forum/showthread.php?t=3866

Thanks but I just spent all my money on a new lift pump. I might try to get one on my next paycheck. I rather get a brand new one!! Just me. Thanks for the help man.

i just took all the vac lines off my cad, pulled the cad part out flipped it around {so its always locked} and put manual hubs on the truck.works great for me!

  Wild and Free said:

If you can justify the 1200-1500 dollar cost of the manual locking hub conversion they are not a bad idea.

Old thread but since it got bumped I'll throw out there that on the '94-'00 trucks (D60 fronts, as opposed to AAM fronts with upside down ball joints) you can swap on Ford balljoint D60 parts and get real bearings and lockouts for reasonable money.