Vaccum line....

OK. 1987 Jeep Cherokee XJ. Under the radiator bottle on back passenger fire wall there are some vaccum lines, most are plugged in but one. There is a red, white, yellow, blue cant remember the other may be green. Any ways there all plugged in but the blue. It is a blue line with a black thing connected to the end but the black thing is not connected to anything. Could this be why my 4 HI light stays on? If not what is it?

That is the famous "unterminated blue vacuum line". My '85 had the same thing. There have been questions about this on the forum from time to time but I don't recall why it is there. The fitting on the end may be a check valve--been a long time since I've thought about it.

The blue line has a check valve/vent. Normal. It doesn't affect your 4X4. I'd say a likely culprit may be with the rest of the lines or how they connect to the TC. The vac switch on the TC and the CAD axle is would be what I'd be looking at.

The switch at the TC and the axle get gummed up and don't connect right. Check those connections and clean everything up. The TC vac switch may be faulty.

Ok. Thanks. don't like loose lines when I see them. Trying to go thru this thing to make sure she is right as rain.

The blue is the vent if i remember right. I ditched my vac lock for a posi-lok a long time ago so I may be wrong.