i have a 91 xj with a 4.0 5 speed and the t-case i don't know but i have 2hi 4hi N 4lo for options if that helps. but my issue is that it goes in and out of 4 wheel drive when I try to engage it. the light blinks on and off i can feel it going in and out. also the light says part time if that helps you to know what Tcase i have. any ideas what this could be?

 

You have the NP231 TC. Have you tried to reverse for like 20 feet or so to ensure it engages before you work it hard?

 

i tried that today and it didnt work at frist it seamed good cause it stayed in the whole time in going backwards than i went forward and the light went off.