I have a 1991 wrangler I bought used and there is a vacuum line coming from the transfer case that is not connected and I can't find where it should go.

Look for the vacuum connector near the brake booster should have a vacuum line coming from the engine to a plastic " T " these always fall off after time use a small zip tie to re-secure the rubber hose to the plastic connector, check all the vacuum connections at the engine and down near the front axle and transfer case.

95 wrangler has a Split front axle, check the unit on the front axle pass. side. Make sure vacuum line are connected and good.

Hi Buganbird22

I pretty much have the same problem. The odds are that it isnt the transfer case at all.

That model year has an electric over vacuum control switch on the transfer case and 2 electric over vacuum switches on the passenger side front fender well near the rear by the hood hinge, they are either green or blue and made of plastic, they both have vacuum lines and 2 wires connected to them.

From there the vacuum lines run down near the front differential where they connect to a slave cylinder. the vacuum routes one way, the slave plunger moves and the differential engages 4WD, the vacuum routes the other way, the slave plunger moves again and the differential disengages 2WD (similar to a 90's model dodge 4x4).

Run this easy test. Label the vacuum lines that come from the top of the vacuum switches on the fender well (front, rear) use masking tape.

Start your truck. (make sure one of those switches has vacuum, put your finger over the nipples where you unplugged the lines, if you feel suction, you got vacuum) trade the vacuum lines, front to rear and rear to front. shift into 4x4, you wont get a 4x4 light, but if you now have 4WD then the problem is in the circuit somewhere between those 2 switches and the master switch on the T-case.

I'll post more as I go. I've been switching mine that way for a week now, because i'm too lazy to fix it in 2 feet of snow.

make sure you get a cap from the dealer. I had similar issue.... bought cap from autozone...still threw the code....thought must be something else.

ended up replacing all the vacuum lines ... still threw a code

desperate, bought new cap from dealer.... problem solved!

there is a vacuum switch on top of the transfer case it applies vacuum when the truck is shifted in to 4 wheel drive . if you connect it to direct vacuum you front axle will be engaged all the time

Our Jeep Wrangler YJ's are equipped with a vacuum module on the front axle. It is used to engage the front axle when the transfercase is shifted into 4WD. Check the vacuum lines on the front axle to make sure they are connected. The passenger side axle shaft has a disconnect sleeve that is moved left and right by the vacuum.

Assuming that everything was working before you started, its most likely that you either forgot to plug something in, or messed up the transfer case linkage adjustment. If you have a front axle with a vacuum motor on it, are the hoses connected at both ends? Also, if you lost any fluid from transfer case or trans while you had them out, make sure you refill them (avoid future problems)

check you vacuum motor and vacuum lines going to the vacuum motor from the top of the transfer case. when u engage your 4WD the valves on the transfer case are opened by a switch on the transfer case. the lines coming from the switch cross the top of the transmission and up the passenger side of the engine compartment. these lines will be red, blue, green and yellow, and often covered by a black sheeth, about 1inch in diameter. check these lines to make sure they are connected. if they are not, the vacuum motor will not engage your front axle. your front driveshaft will still spin, because the transfer case is engaged as normal, but the right front axleshaft is a 2 piece system engaged by this vacuum motor. if they lines are messed up, the motor will not engage the axle collar connecting the 2-piece axle. if your vacuum motor is working, then you might have a broken collar, or perhaps a broken axle shaft. but it's probably just the vacuum hoses or the motor :) i hope that helps!

Sorry, but my solution would be to take that drive back to the dealership, if he has a warranty. This is a hands on type deal, you have to trace everthing with your hands. Now it sounds to me like it could be in the electronics. You have to go to the differential, find the vaccum lines, if equipped, some are not, then trace them back to the motor and make sure they aren't cracked or broken. I hope this solution was helpful, please rate. Thanks

check the wires on the transfer case mine got melted by my exhaust somehow and i just have learned to deal with it lol.