4x4 won't engage

[Yfzryder450]

I just bought my first xj it wasn't running I got it started an running good but took it out today to play a little bit....when I tryed to lock it in the t case engaged an the drive line was spinning at the dif but would not lock in high or low....it's a 97 an any info would be greatly appreciated

[cantab27]

hi mate ...have ya had a jeep before...might sound silly but how did you engage 4wd ..what did it take to get her running again...

[Yfzryder450]

Yeah I had a wrangler before this an iv had 4x4s my whole life I tryed several different things an the tcase engaged but the dif would not

[Yfzryder450]

And the wiring was butcherd an it was missing the power steering pump is why it wouldn't run an that's why I was wondering if it could be the actuator switch...an if I'm not mistaken it screws in the t case?

[4.3LXJ]

Does that 97 have a vacuum disconnect on the axel?

[Yfzryder450]

Yes it does

[nickxj94]

Linkages in a bind maybe, the 97 shouldn't have vac disco unless someone swapped it out for one, the front shaft will spin all the time even in 2x4 so will the axle shafts

[Yfzryder450]

Well it's defiantly gettin the lower gear ratio when you put it in so I belive the t case is going in if it had the vac disconnect wouldn't it be on the passenger side like or could that be something else

[4.3LXJ]

Kory, you are not supposed to have a disconnect. Unless the transfer case has been changed too, you cannot engage it with what you have. If it is not engaged, it will not allow you to have 4WD

[Yfzryder450]

Ok well it does have the vacuums actuater if thats whats on the axle which is the only thing that should be there right? I could be wrong on the year or it may have been swapped I'm not sure..the t case stick shifts smooth an stays in every position as it should

[4.3LXJ]

There should be a vacuum switch on the back of the transfer case along with a collection o f tubes that go to the front axle

[Yfzryder450]

The switch should have four wires? An is the switch a common problem?

[4.3LXJ]

If it is for the vacuum disconnect it will have four vacuum hoses that look like colored wires

[Yfzryder450]

Ok well I figured out its a 90 An should I try replacing the switch?

[prcjeep]

I think what most people do when the switch is out is to swap out that axle shaft with one from a later dana 30. Im not sure what year, but the shaft from one without the vacuum disconnect should swap right in

[ParadiseXJ]

Ok, so you have a '90...but you thought it was a '97 ? Did you buy it from someone who told you it was a 97 ? Does the registration say 97 ? Anyway it's a '90...Renix.

Your Renix axle is engaged/disengaged via vacuum. The 4x light is also operated via a vacuum switch. If your vacuum source OR any vacuum lines on the passenger side are compromised, you don't have 4x.

I, and many others with Renix a "Central Axle Disconnect" (CAD) axle have been frustrated by this set-up and there is a simple, easy, permanent fix that is also reversible if you decide you don't like it. This is just one link to the same job.

http://www.cherokeeforum.com/f51/free-d30-cad-bypass-91-a-38629/

This took me about an hour to do. 55 minutes of that was spent cleaning the whole area, polishing the aluminum cover, letting the RTV set up a bit, and lying under the jeep admiring my work. I liked it so much on my 90 XJ that I did it on my 88 MJ...that job took me 20 minutes...it was already clean. :D

The ONLY downsides to this mod is that your front shaft will always be spinning...just like a 91+ XJ and may let you know if you have a bad front u-joint...I'd wanna know anyway....and the 4x light won't work without a little more modification.

The transfer case engages via linkage, and since the front axle is now locked, the transfer case linkage is the ONLY way it engages or disengages the 4x (just like a 97). The vacuum lines to the transfer case and the axle should be plugged.

[XJ Wheeler]

As ParadiseXJ said the vacuum lines on a CAD Dana 30 get old and deteriorated with age. This leads to cracks that leak, and it can't hold pressure so it doesn't engage the shift fork that locks the two piece shaft together. Basically. Leaks can be hard to track down and vacuum lines are cheap and easy to replace. This would be if you wanted to keep it working like stock. Otherwise i would swap out the shaft for a one piece.

[Yfzryder450]

I was told it was a 97 an never looked at the title cause it will never be on road I looked at the it today an it is a 90 after getting it back to the shop an doing a little searching I found a vacuum line disconnected on the passenger side close to the firewall hooked it up an the 4x4 works great I am thankful for the help it's much appreciated

[XJ Wheeler]

Awesome, glad it was an easy fix.

[ParadiseXJ]

Awesome, glad it was an easy fix.

That's great!! Nothing like an easy fix. Just a note though about eliminating the CAD.

Free
Easy
Solid
No more vac lines to break on the trail.

I waffled on doing it for years until I finally bit the bullet and did it. The 4x engages now without any worries about a faulty vac line. Swapping out the shafts for a 91-92+ axle also sounds like a good alternative.

[4.3LXJ]

I have shimmed mine over too. Nothing wrong with doing that. Those disconnects were a gas milage thing. Having it turn all the time will let you shift into 4WD easier. Won't make any difference on shifting out though.

[Yfzryder450]

Ok great thanks for the extra info I will try it out

[Yfzryder450]

Hey guys had another question for ya I broke the passenger axle shaft an was gonna do this mod when I put the new one in do you hook the vacuum lines back up or plug then?

[4.3LXJ]

You can remove the whole harness and then plug the red line off that feeds the whole thing

[Yfzryder450]

Ok thanks for the info