Okay so i got an 01 with a np 231 t case. i noticed the other day that when i pull the handle back to engage 4 wheel drive, my part time light will not come. it has always worked in the past no problem and doesnt work for 4 lo either. I've never had 4x4 problems before so i dont really know how to diagnose this.

 

First you need to figure out whether or not your 4x4 actually works.

The "Part time" light is irrelevent to the 4x4 actually working.

Easiest way in my opinion is to shift the jeep into 4lo. It's super low and torquey and you should be able to tell pretty quickly whether or not 4lo is engaged.

 

If it in fact is not going into 4 WD the first thing to check is the linkage, common and easy to fix most of the time could have just came loose.