Part time 4 wheel drive problem?

I have a 1989 Jeep Cherokee Pioneer- No , I'm not taking it to the bone yard! Has 215,000 on its 4.0 stock engine.Winter has struck here in the northeast. Yesterday, I went to put it in 4 wheel drive, the console lever moved to all positions, but it remained in 2 WD mode. The orange light monitor on the left end of the dash cluster did not come on, I tried the Transmission power mode rocker switch- (power **comfort), switch moves OK but the monitor light within the switch didn't light up. Possibly , unrelated but I had the crankcase position sensor replaced a few months back,due to an intermittent start problem, by so called professional technicians, but it turned out they only found the problem after I suggested they try a replacement crankshaft position sensor, but to be kind, these technicians were still in short pants when this vehicle was made..


Some Jeep knowledge would be appreciated. Many Thanks, Cheers, Ralph|||I believe it has the vacuum disconnect for the front axle, so I would look at the vacuum lines running to it to make sure they are connected. It could also be an issue with the shifter linkage to the t-case.





If both of those look good, then it's also possible the shift fork in the axle is stuck.|||to elaborate a little more on what Jimny just said, these trucks ( and most from this era and on) have automatic locking hubs, instead of the crappy old system where you had to get out of your truck in the freezing cold to activate 4wd. Most are pneumatic using engine vacuum to lock the hubs. So your problem could easily be a simple vacuum leak. The fact that the indicator light didnt come on on the dash makes me think you just have a shift linkage issue. One thing you can also try and do, since it is so old and worn, is to shift it into 4wd while the vehicle is moving at 5mph or so. Get the truck rolling, shift the tranny to neutral, while still coasting try and shift into 4wd. Ive found that as the gears and parts inside the t-case wear it sometimes needs some help lining up the gears inside (thats actually the way most Jeep 4wd systems are supposed to be shifted anyways).