XJ hopping in and out of 4WD

Hey all. New to the Jeep community... New to 4x4. Just picked up my first Jeep about a month or so ago.

:helpme: At first snowfall today (Colorado) my Jeep decided to get fussy. Shifted into 4H and in the middle of driving down the road my "Part-Time 4WD" light started flickering and before I knew it I was sideways!? Cautiously driving the rest of the way, my light would bounce on and off and my 4WD would engage and disengage for no reason. Tried holding the stick in place with no avail. Is this electronic or mechanical??

No modifications / 1990 Cherokee Laredo / AW4 / I6 / Unsure of transfer case and gearing.

You could have a vacuum issue with the vacuum disconnect system on the front axle if you have a 231 transfercase. One way to identify your transfercase is the shift pattern, if you have a 2H-4H-N-4L pattern, its the 231. An extra selection labeled "4 full time" between 4H part time and N means you have a 242.

If you do have the 231 t-case, that year means you have a disconnect D30, that uses 2 piece passenger side axle shafts. There is a little vacuum canister on the passenger tube that slides a collar over to connect the two shafts. It seems possible you could be having an intermittent vacuum problem perhaps with this system.

Agree with Begster.

There is a vacuum reservoir "ball" or "capsule" behind the front bumper, passenger's side. The hard vacuum line(s) like to break in the battery area.

The three-line connector on the vacuum motor mounted on the passenger's side of the front axle likes to pop off.

The vacuum motors can and will fail.

The vacuum lines from the transfer case switch that run to the vacuum motor on the axle can/will break.

Vacuum motor testing procedure see my post here: http://www.naxja.org/forum/showthread.php?t=1037893&highlight=vacuum+motor