i just got a 99 cherokee and i found out my 4x4 does not work..at all. i can shift into 4hi and low and it seems to sift into those fine, but nothing is engaging. the dashbord lights do not come on or anything. i was told to check my linkage by a friend. does this sound right? and if so, how would i go about doing this. im new to jeeps and eager to learn, so any walk throughs would be great, thanks a lot.