"Part Time" Dash Light

Ok everyone...88 Cherokee, 4.0, Standard 5 Speed Trans. I had the occasion to put the vehicle in 4XHi the other morning to go to work, snow had come to Northern NJ. When I put it in, I got a "Part Time" light come on. After manually shifting range back to 2XHi, the light won't go off. I start it this morning, lights out...I spin tires on the road in front of my house, lights on, even though it's still in 2XHi. The light must love me, it hasn't gone out since.
Does this drive train set up have the capacity to activate 4X4 when wheels slip? Is this a switch that's got crud on it and hanging up? If it's probably just a switch that needs to be cleaned and lubed, where is it?
I don't want to be driving it in 4XHi now that the roads are dry, though I really don't think it's in 4X mode. I'm going to cruise the Hayne's manual to see what it says, but you see where I came first with this question. I guess I just don't know what to expect from this system never having owned one and first use/need was yesterday morning on my way to work.

Stephen

try to dissconect the negative battery terminal, and then put it back on and see if that helps, mine 4wd goes off and on when im wheeling and I hit hard bumps, its awesome

Make sure all your vacumn lines are connected,and there are no breaks in the lines.
Pull the inst panel and make sure the connectors on the back side are in good and tight............my .02