While diagnosing my rough running condition on my XJ today (I finally have a day off), I noticed that my vacuum hoses were disconnected at my Front axle. When I connected them, the Part Time light came on. Until then I've never seen it before. Also, the 4WD light does not come on when in 4L.

I have verified that the NP231 has good linkage bushings, and that when I push her back into 2H the front driveshaft disengages. I did have to roll backwards to get the driveshaft to unlock one of the times I tested it though.

I tried shifting the transfer case both stopped and rolling slow (on compacted clay/small rocks). Doing this I noticed the shift to 4L is difficult if the transmission is not in Neutral. The shift from 4H to 2H and Vise-Vera was much easier while driving than while stopped, unless the transmission was in Neutral.

My question is: What is keeping the "Part Time" light on when I connect the vacuum at the front axle, even though I know the Transfer case in in 2H?

Thanks in advance.

 

Make sure your Vac hose are hooked up correctly.
Print this pic to help.

 

This is making me think it is that vacuum control switch. Everything is hooked up as per that diagram (as far as I saw earlier) and vacuum is held at the front axle, when I unplug the rubber boot containing two vacuum connections I can hear the hiss.

 

Err.. Double post, sorry.

 

Verified that the front DOES NOT lock in. I tried backing up a rather long up-hill in 4H and 4L and the front wheels did not spin. The driveshaft is engaging, but the hubs. The shift fork is not engaging, correct?

What else should I be looking at? I plan on pulling the housing and checking that the fork moves by hand. Anything else I should look at while in there?

 

Put vac on one side of the vac motor it should retract, vac on the other it should extend. You can do this when it's out.

The fork is held onto the shaft with E clips. It should not wobble perpendicular to the shaft. It will rotate on the shaft.

Make sure the collar moves freely from axle to axle.

It's common for the forks to break. Someone makes steel replacements. I ran a cable setup for years and shifted carefully and had a cast fork last 9 years!

You can also "rig" the fork to stay engaged with a bolt and nuts replacing the shaft and vac motor. I also did this for a while.

The best repair is to get a one peice shaft and seal kit and do away with the disconnect all together.

I replaced the entire disco housing for a non disco housing. Check it out on Daily Driver Jeep Club fb projects and wrenching

 

The cable setup is what I though of doing even before I found this problem.

I didn't get a chance to tear it down tonight. Tomorrow seems to be a light day at work so I'll be able to do it then.