Hey guys, i have a 91 XJ Sport with the np231 transfer case and 4.0. My part time 4wd light is on, the front driveshaft stays engaged, but hubs aren't locked in. I can switch from 2, to 4hi, to 4lo, and back through fine. 4wd system works great, but its like it stays partially engaged all the time. i tried adjusting the linkage on the transfer case, but it didn't fix the problem. I also checked the T-case fluid level, and its fine. I have to drive 80 miles every day to get back and forth to work, but I haven't been going over 55-60 because I don't want to mess anything up more than it already is. Any ideas?
-Thanks in advance!
D

 

First off, most likely your 91 leaves the front end engaged all the time. 91 coulda been a split year. Got a contraption like the photo below on your front axle?

Sure it's in 4wd? It would be bucking on turns and you'd surely notice that.

 

if the front driveshaft is under power in 2wd, the problem is in the transfer case

the light could be stuck on by a bad vacuum switch or the front axle disconnect could be rusted in place