2000 Ram 1500 5.9 Auto Manual Shift 4x4. Last winter I started to have problems with 4x4 staying engaged in Hi. Have had 2 repair shops tell me two different things. One a new transfer case another an $800 ft axle rebuild. NOT! Reading the forum for ways to diagnose the problem, I found that I have no change in vacuum coming off the TC, when I move the shifter. Cad moves with what vacuum is there just not far enough to totally engage or disengage 4x4, i think. What do you guys think , could it be as simple as the vacuum switch on the TC? Great forum and lots of good info
Thanks

 

My Ram is 2wd...so I don't know. SOmeone else will poist up.

In the meantime, there is a factory service manual you can download in the FAQ/DIY section that will be useful!

 

All that is happening more than likely is your CAD isn't disengaging, cause your 4WD light to stay on.
Once you shift the t-case out of 4 hi, into 2 hi, it is out. Period. The CAD is what makes your light come on. Checked the vacuum lines yet?

 

http://www.cseoffroad.com/450400.html


Do it.

 

Read this, http://www.dodgeram.org/tech/repair/..._engagment.htm

$2 to $10 fix most likely.

 

had the same issue awhile back. found out it was the steel vacuum lines that go from the transmission cross member, to the frame rail for the vacuum lines for the cad unit.

just get a 25' roll of coated brake line, remove old steel vacuum lines, and measure them. cut new brake line, bend line in the shape of the original, and re install. not hard to do, and take maybe 10 minutes.

 

read zman's link above to understand the vacuum and the cad engagement.

decide whether your problem is the t-case jumping out of gear, or the axle engage/disconnect not holding.

put the truck up on 4 jack stands where you can safely operate it. test the 2wd and 4wd engagement.

open up the cad and test the vac shift motor moving the fork back and forth. test the collar sliding over the inner axle to engage. check for burrs on collar or axle splines that might prevent it sliding properly. check bushings for play and axle alignment problems.

 

Thanks for the advice. I have some vacum on one of the lines from the transfer case but not the other. The cad does move but it seems like its slow and may not be moving far enough. I will pull the cad and check the drive axles for burrs and alignment before I replace vacum lines. I dont have a vacum gauge to check this and don't want to spend the $50 on one if I dont have to. Thanks for your help and posts so far. I am really hoping this is the vac switch on the transfer case. I found one online for less than $20.

 

the vac switch is an easy and cheap replacement. the big connector or vacuum lines is "keyed" with a notch, so it only fits on one way.

vac on one line (4wd) pushes the shift fork to engage. vac on the other line (2wd) pulls the fork to disengage. its simple, but prone to failure.