sporadic 4x4 issue

I have a 1991 jeep cherokee 4.0l and my 4x4 light comes on but it rarely engages, as soon as it does i try to go through some snow or something and it kicks out. I lookat at the t case and all the connectors and everything looks fine, its a 231J case and the axle i believe is a dana 30. i looked at the connections on the axle and cleaned them as well, but the motor is way loose and whoever had it before me ziptied the connector on (i'm assuming because it was loose and kept coming off). there is no vacuum line attached to the front axle and i see one off of the tcase but it stops by the bell housing. I've looked all over and i cant find any diagrams on how or if that is supposed to attach to the axle. If anyone has a diagram or can help it would be appreciated. Thanks

anyone????

if you have a 231 t-case, you probably have a vacumm disconnect front dana 30 that is causing this. look at the back-passenger side of your front axle and if there is a bulky black and probably grease covered "thing" attached to the axle housing you do. that vacuum line, i think, should be connected to it.

if the "thing" (vacuum actuator) is not there and its just plain axle housing then I have no idea.

there are actually four vacuum lines that go to the transfer case and front axle shift motor. Here's a vacuum diagram



And heres a front axle shift motor diagram



there should be a transfer case switch that sticks out of the front (input side) of your t-case
they go out fairly often and are about 15 bucks. The shift motor however is much more expensive

The ty wrap was to keep the connector on the shift housing at the axle - it's factory. When the connector gets soaked in grease it swells and starts leaking the vacuum to outside air. The vacuum diaphragm will also be affected and deteriorate eventually to the point the shifter won't move. Voila, no 4WD.

If you remove the housing and shift it, the housing lever should move. If it won't, you can block it to the engaged position, flip it, and reinstall, locking the axle in drive. '92 up are factory built without the disconnect and run that way all the time - as has mine the last 4 years. I even pulled all the vac hoses, etc. I see no difference in mileage, and I get 4WD when I shift it, no matter what.

You can repair it, mod it on permanently, or get a cable to manually do it. Options are yours.

so... i got under there and when i pulled the connector to my t-case i made a hissing sucking of air noise, i hope thats good. i followed the hoses and that looks good, when it gets by the bell housing on the passenger side 2 hoses go up and 2 go to the front axle. I pulled off all the connectors up there clipped the zip ties and cleaned EVERYTHING in that area up. put clamps on the rubber hoses that connect to the shift motor on the axle. That portion looks good now, BUT... the 2 hoses that go up, one connects to a 3 way split of the lines, the other has a screw in it and it just stops. Any ideas on that one? Also one of the lines off the slpit goes up in front of the battery and disappears in there, what does that go to?? Havent had anymore time yet, i did all that at 11-1 last night. I'll test the 4 wheel drive tonight to see if its engaging but at least i got that cleaned up, it used to have a hell of an oil leak, not anymore, lol.

i tried it out and its still not engaging, today when i started it, i heard that sqeal like a vacuum leak, but i can hear it inside the cab as well as outside about the same noise level, maybe a lil more outside. but it always starts on the inside. if i can find the noise/leak and it still doesn't work, it'll be time to start throwing money after it. Please anyone who can help, please let me know where there is any vacuum spots inside the cab that i'd be hearing, also if you know whats vacuum related thats on the passenger side right behind the front bumper.

There is a vacuum canister that stores vacuum for the four wheel drive system on the Pass. side mounted behind the bumper that's where that line is going. Is the line with the screw in it blue? If so it is a vent. The other one that tees should go to the indicator switch. all other vacuum line connect just below the blower motor and pass through the firewall. Check all of these spots. The vacuum lines should be plastic instead of rubber and wrapped in wire loom so make sure this is what you are seeing.

hey buys those lines running from the vaccum pump go up to the top of the motor on the passenger side, my blue line is not connected, should it be, maybe thats why my 4 wheel drive isint working, but like superflie said, my lights coming on and i feel the jerk like it does when it is going into 4wd, but i got stuck intentionally and my front wheels would not move, whats this blue line

the blue line is a vent and shouldn't be connected to anything. It should have a check valve on it though.

OK....i went out and bought a vacuum tester and started testing at the junction on the passenger side of the vacuum lines. The one going to the t-case leaks fast, that extra line from the t-case that comes up and is plugged, is plugged with a screw but seems ok. I think those lines that connect to the front axle aren't sealed or something. How exactly could i test the 4 wheel with out pulling that shift motor housing??? Can i pull the 4 wheel lever and start it, then get under it and move that shift motor?

i tested the lines and fixed the ones that were leaking, for the most part, it still leaks slowly. so i lifted the rear end, started it up and shifted to 4 wheel. the 4 wheel light came on and i let off the brake. I could hear the front axle grinding like it was trying to shift in but it never did. I have a feeling this is not good. please help!

ok, the vacuum leak is totally fixed and it still grinds