here you go.
http://dodgeram.org/tech/repair/4X4/4x4_engagment.htm

 

Guys sorry to revive this old thread but I'm still lost with this truck... I've tinkered with it but still not straightened it out. I've tried shifting to 4hi while driving and it still won't do a thing. Any way I try to go to 4hi I get absolutely nothing but I can stop the truck and put the transmission to Neutral and shift the 4wd to 4hi (which won't engage) and then over to 4Lo and 4Lo will engage and work as it should. The only drawback to that is when you try to go back to 4hi and back to 2hi you can't because 4hi won't engage. You either have to turn the truck off and try to shift out of 4Lo or grind it out of 4Lo (which I know can be catastrophic). I'm lost... Any ideas? Thanks everybody...

 

Pull the stick back to 4hi, crawl under the truck, and try and turn the front driveshaft. Can you?

 

With the stick in 2HI the front shaft turns freely - With the stick pulled back to 4HI the front shaft doesn't turn, only maybe a couple degrees back and forth just barely

 

If you look on the back pass side of your front axle, there should be a unit called a CAD ( central axel disconnect ) this allows the front axle to not put drag on the drivetrain with the shift on the fly, basically this is the "new" locking hub system, this system works off vaccum, there are two lines that run to your transfer case, to a switch. This switch is activated by linkage inside the transfer case when you go into 4wd, and switches the vacuum to the according line going to the front axle. One will be no vacuum, one will. (if the system is working right). This switch on the transfer case can sometimes get stuck and not switch back and forth or even leak the vacuum threw the case.

I would start by seeing if one of the 2 lines going to this unit have vacuum, if so, take the line with the vacuum and mark it, then pull back into 4wd and see if it switches lines, if not switch is to blame, if so then the CAD is to blame. If there is no vacuum just trace the lines back to the engine bay, one will vent to open air, one will be vaccum, be sure the vacuum is hooked up with no leaks.

-Cheat

 

ok first thing in the morning I'll try that... if it is the things you're talking about would it be able to go into 4Lo like it has several times? I can pull it back go over and to 4Lo and engage with no problem but you can move the shifter back and forth from 2Hi to 4Hi and nothing happens. Does the 4Lo engage in a different way?

 

When you go into 4L, you are just doing it to the back wheels because the CAD (front hub) is unlocked, allowing the front differential to spin freely in 4wd high or low.

 

Man I appreciate the help and I'll check what you said to in the morning. When I go to 4Lo it actually feels like the front diff is engaging (feeling and sound from inside cab) unlike when I just pull to 4Hi and nothing feels or sounds. I messed with it in my back yard in the rain one night. My yard is sloped so I spun it up pretty good but when I pulled it back and over to 4Lo I took off up the hill. When just pulling it back to 4Hi all I did is the same as 2Hi.

 

Just find you a nice unneeded spot and lock it in 4L and floor it for a few seconds to spin and see how many tires spun and which ones. From what I've experienced and heard, the back ones should only spin according to what your discribing.

 

Sounds good man thanks for the help. I'll give it a shot tomorrow. Thanks again...