ok i have had it!!! first it wouldnt go into 4wd so i put a new shift motor on axle and replaced all the vacuum lines from axle to transfer case and replaced switch on transfer case. then when i drove it would pop out of 4wd. i put a check valve because there wasnt one just as the vacuum line leaves the intake. and replaced the lines at the top of the motor and disconnected my cruise control. that didnt seem to do anything! at the begining of the day today i would be able to drive to the driveways to plow in 2wd and when i got to driveway i could put it in 4wd and it seemed to be fine. now I cant even get it into 4wd. the light comes on showing its in 4wd but it wont engage! i hear it trying to engage but it wont. Im losing my mind with this truck!! !!!!! i use it to make me money and lately i am plowing to pay for repairs!!!

 

best not to throw parts at it and expect it to work...

you need 17" at the red line in 2wd and 17" at the black line in 4wd.

if the aformentioned requirements are met, dissasemble the CAD and check for binding in the shift collar (burrs and wear are a likely cause here). check play in the output shaft bearing and outer shaft bushing, as well as the u-joint. if all seems good bench test the shift motor.

 

If it is the cad that is the problem and i knew that for sure i would probably switch to the cad delete so that you can manually lock the axle in.

 

thats a viable option and some HIGHLY reccomend it, but if it were me, id spend $3 on some vac line and call it a day ...assuming thats your problem

 

if your 4wd light is coming on/off normally (and staying on/off correctly), your cad shift motor is probably working ok, but if you're not actually holding 4wd, you might have a problem with the collar, shift fork, e-clips, axles splines or collar splines.

remove the cad and inspect the collar and splines for damage. if not stripped, just set it semi-permanently to the engaged position, and leave it there until winter is over.

do this. slide the collar so its fully engaged. identify the 4wd port of the cad and attach a vac line directly to the engine manifold. pull a vac on it to create the 4wd shift. line up the fork and reinstall the cad. plug all the other vac lines to prevent contamination.

i hate my cad too. after fixing it 2 or 3 times i installed a posilok. after fixing it a couple of times, i'm not as in love with it as i used to be, but its still better than the stupid vacuum system.

 

can someone explain that manual lock in / posi lock how does that work? it doesnt use vacuum at all?

 

it uses a manual cable to slide the fork and collar back and forth. no vacuum used. the cable is attached to a push/pull **** in the cab, so you can engage/disengage the axle lock as you please. i'll find a pic.




http://www.4x4posi-lok.com/app_dodge.html

 

Regardless of what direction you go, fix oem or get the posi-lok. You need a vac gauge to verify vacuum. If it's not right, the leak needs to be fixed for proper operation of other components whether you use the cable or not.