You have an NV247 transfer case. You don't have AWD. The NV247 sends power only to the rear wheels (that's 2WD) until one or both rear wheels lose traction. Loss or rear traction causes the NV247 to send power to the front. In that case I guess that it could be called AWD, but 4WD is probably best. With an NV247 you have either Quadra-Trac II or possibly Quadra-Drive. Most QTII WJs come with open differentials, so if one rear wheel loses traction followed by loss of traction by one of the front wheels, you get stuck. QD has the additional feature of Vari-Loc (a type of limited slip) differentials. Usually, when one wheel on an axle with Vari-Loc loses traction, torque is still applied to the other wheel. Because of the NV247 transfer case, when one rear wheel loses traction, even with Vari-Loc, there is still transfer of power to the front.
Now, what system do you have? Explain what's happening that makes you think it's not working.