So I recently acquired a 98' ram 1500 4x4, and had a trans rebuilt and a new wheel hub put on it.... today I shifted into 4-hi for the first time, and when I went back into 2-hi the front end is staying locked up and the 4wd light is staying on... I tried reversing, then pulling forward. I've put the truck in neutral with my foot on the brake shifted the transfer case into neutral, shut it off shifted back into 2hi then started the truck. I've shifted down into 4-lo and back into 2hi and the fron end will not come unlocked.... it's stuck in 4-hi and I don't know what to do..... the vacuum lines seem to be fine so I have no clue what it could be.

 

The t-case is disengaging when you shift, it doesn't have a choice, its purely mechanical, the problem you are seeing, is the CAD isn't disengaging. It's vacuum powered. Check the vacuum motor on the passenger side of the front axle, should be two vacuum lines going to it, make sure you get vacuum on the outboard port with the t-case in 2Hi, engine running. (trans in park. e-brake set..... don't wanna get run over. )

 

thanks for the help... I dove in a little deeper. I unbolted the whole thing and manualy "shifted it back over into 2wd while the t-case was still in 2-hi... I guess I should replace that diaphragm??? I pushed the shift fork over and the "o-ring locker" also realigned them together bolted it back up now my driveshaft will spin freely again and i'm in 2wd.... next question is will this thing go exorcist on me and lock the front end back together while i'm going down the road?? I test drove it and it was fine, but i'm concerned... thanks again.

 

welcome to df.

the vacuum cad will always fail and do the opposite of what you want it to do.
the most common problems are broken vac lines between the tcase and cad, and a rusty/sticky shaft inside the cad not wanting to slide.

its fun to fix the first couple of times, after that its a pita. don't spend any money on it.

look into a posilok. alloy has them a tad cheaper. its a manual cable and lets you have 2wd low range, which is nice because your steering doesn't fight you.

 

since I slid everything over and am in 2hi, this thing isn't going to just try to lock itself up while i'm going down the road is it????????????

 

it'll be a rare day when I need 4wd. I was just trying to see if it worked, since I just got this thing a month back.... worried its going to lock itself back in going down the road though.

 

unlikely.
understand that its vac controlled via the t-case switch.
so you should have vac on the 2wd line that's pulling/holding it disengaged.
then vac on 4wd when t-case is in 4wd, and that pulls/holds it engaged.

if you're missing vac on either 2wd line or the 4wd line, then it might shift one way but not the other.
if you're missing vac on both, then the fork and collar might flop around.

like heyyou said, verify you have vac on each line at the appropriate tcase gear - 2wd or 4wd.

and its good idea to use 4wd at least once a month to keep it from freezing up.

and read this...
http://dodgeram.org/tech/repair/4X4/4x4_engagment.htm

 

Guys, I can't thank you enough. I've only had the truck about a month and a half but god do I have some wrench time, and a newly rebuilt trans in it... reading the engagement link you provided is what helped me decide to take the diaphragm off earlier. good thing I could not get the vacuum tree off the t-case, and decided to mess with the diaphragm...lol. how exactly do I check that i'm getting "vacuum", and will it be blowing or sucking, or will one be blowind the other sucking, or just one sucking???? sorry for the newb questions. i'm trying to learn how to work on the ole' dodge. I despise paying for labor... let me know how to check for vacuum and I think i'll be set from there, and I will most definitely be getting the posilock as soon as I can afford it..... I hate this vacuum set up already. what happened to the good ole days of manual lock outs?? thanks again guys you rock!

 

Reread post #2.
There are 2 vacuum ports on the diaphragm.
Remove the connector.
One line should have vacuum when in 2WD.
The other when in 4WD.
With nothing holding the shift fork or collar
you are inviting Murphy to come and move
it around.

 

no blow. only a suck or a no-suck.
to test, first LABEL, then simple remove the rubber vac line at the cad port. with engine running place your finger over the end of the hose and feel that its sucking. a more precise way is to connect it to a $15 vacuum gauge, and measure that its drawing a number of about 15-20.

test one with engine running and t-case in 2wd. test the other in 4wd.

the vac lines run a long way from the tcase to the cad, and are stupidly routed down, and under the transmission instead of over the top. they get snagged in the dirt, rocks, sticks, etc. even though its hard pipe under the bottom, they still get bent and crushed. if you have a problem with the lines, just run new rubber hose from the t-case, over the top, and over to the cad.

the switch on the t-case has a large rubber boot that slides down over it, which just pulls off. it's 'keyed', so it only goes on one way. then the switch screws in. it sometimes fails, but a simple vac line failure is much more common.