Why all the 4wd vacuum tubes

My son has acquired an old 1992 4cyl Jeep wrangler YJ that had many disconnected lines/wires/tubes that we got mostly figured out and basically connected to the point where it's running fine. One area that seems to be functioning OK is the front 4 wheel drive system that when the manual lever is placed in gear (up on blocks), even though all the vacuum tubing is messed up and not totally connected, looks to be engaged because the front wheels are turning. This is fine with him because he only wants to use it in winter on snowy roads. My question is.. is it really in 4WD or just playing possum ? That vacuum module on front axle.. does it possibly engage something when working correctly that may be stuck in the engaged position ? What's going on here

 

Sounds like someone just ran a vac line to your front axle actuator. What that will do is engage your front axle full time, regardless to transfer case position. I am currently going to have to go through mine as well (on my new to me 93) Been through this before though. What is SUPPOSED to happen with all the vac lines, is that there is a vacuum switch on your transfer case, which is supposed to have full vac at one of the ports (search for online drawing) and depending on transfer case position (eg. 4 lo and 4 high) would send vac to your actuator, thus sliding a pin lock in the front axle, locking the gears, like you would on an old manual setup by locking the hubs. This in turn sends a signal via the electrical connector near the actuator to the gauge cluster illuminating the 4wd light in the pod near the steering column. If this is all too much for you, there is a kit that can be purchased to elininate all of this, by adding a cable driven actuator plate at the axle, which i believe retains the electrical contact to illuminate the dash light. Hopefully you check back to read this……forums are way less active then in years past i am starting to notice. Which is sad. Good luck!