Jeep YJ 4X4 not working

[Max]

Does anyone in Boulder have experience troubleshooting the 4wd on my jeep? It decided to stop working yesterday right when it started to snow :(

720-244-0445 or pm me here.

[Patrolman]

Some tips. If you have manual locking hubs, lock them and then reach underneath and try to spin the driveshaft (engine off of course). It shouldn't spin. If it does, then likely some issue with the front axle/hubs.

If that is all fine, unlock the hubs, and then try putting the t-case in 4wd. Put tranny in gear if manual trans. Again, try to reach underneath and spin the front driveshaft. If it spins, you may have an issue with the t-case. This will narrow it down.

I guess all this assumes that you actually have a front driveshaft. ;)

Let us know how it goes.

[Max]

Locking hubs, meaning turning a knob on the front wheels? No I don't think so. It's a 1995. I failed to mention that the 4WD indicator on the dashboard that usually lights up does not. I don't think the light bulb would fail and a mechanical issue underneath happening a the same time...

I can try to spin the driveshaft tomorrow in the daytime.

[Hypoid]

Light bulb aside, how do you know it's not working?

[Brody]

If you have on older XJ with the vacuum assist front engagement, then what very well may have happened is that the vac mechanism got some moisture in it for some reason and it is now frozen. I had a 1990-91 Cherokee awhile back when I lived in the foothills and had nothing but problems with that system when it got cold. If I had forgotten to stick it in 4WD the night before after I had driven it home, and it got cold at night with a lot of new snow, I wouldn't be able to get out of the driveway in the AM because it wouldn't go into 4WD.

I tried replacing all the vac lines, and even took apart, cleaned and lubed the vac assist and still had the same problem. I finally went with a simple cable conversion kit. Pull the damn cable, stuff slides in place, and it's in 4WD. I liked the cable, had absolutely no issues with the 4WD after I did it, and wouldn't even bother trying to sort out any vacuum related stuff if I had problems related to that. I would almost immediately replace it with a manual cable.

There are quite a few versions out there. This is one:

http://www.drivetrain.com/parts_catalog/accessories/posi_lok_front_differential.html

You also didn't mention whether the 4WD stopped working when you were in motion or stopped.....or whether you simply couldn't get it to go into 4WD when you got in it to go somewhere. My replay is based on the latter.

[Java]

I think Brody's got it. I had an 88 and put a 4x4posi-lock cable to replace the vacuum actuator. The light on your dash is activated by the shift mechanism on the front axle, as the shifter slides into place it hits the switch, so if it's not engaging the light will not go on. The shifter is a two-prong fork that fits over your axle shaft and simply slides a splined sleeve over some splines that conncect the two halves. You can open the mechanism (just a couple of bolts on the rectangular cover on the axle) and slide it over by hand, and leave it locked. Just raise it a hair off the axle, look for the fork going into the axle and slide it towards the passenger side with a screwdriver, you'll know when it's engaged. you may have to spin a wheel a little to get the splines to lne up. I've heard of guys welding these just like differentials, it works fine. A friend in FL filled his with JB weld to lock it. With the cable I always just left it locked up so I had shift on the fly. The whole deal is just an overcomplicated way to save a minimal amount of fuel, if you swap to TJ shafts you can just put a plate over it.

[Max]

I THINK I FOUND THE PROBLEM


Once I actually crawled under there in the daylight, haha.


Tip: If you see something clean and shiny under your truck, there may be a problem!

Thanks for the help fellas. I'm glad I got it working now that the snow is melting again :D

[Brody]

Good for you and glad that it was a simple fix!

[Popsgarage]

Good news, simple fixes are the best fixes!

[Patrolman]

Absolutely. Look for the obvious. I wasn't sure if your Jeep had a disconnecting axle or hubs. Hubs with a manual shifter are the easiest to diagnose. The other stuff can drive you crazy sometimes.

[Popsgarage]

I wasn't sure if your Jeep had a disconnecting axle or hubs.

X2!

[Java]

LUCKY!!! That's great to have it fix so easy, especially in this weather! :thumb:

[Heather]

Whew! That exact same thing that happened to Adam when Robyn and I were on a run with him. Crazy how such a simple little connection can play such an important part...so glad it was such an easy fix for you!

[glacierpaul]

Max, you are ASE certified now:thumb: :D