It depends on how mechanically inclined you are. It could be a couple of different things, start easy first, check fuses and connections to the switch and t-case motor. Most of the problem seems to be the t-case motor, it has an encoder motor sensor inside that goes out and causes the t-case module not to know what range its in. You can either buy the whole motor or just he sensor and seal. Just the sensor is the cheaper route. The whole motor is around $200 and you just bolt it in. That is the problem about 70% of the time. Also could be your switch on the dash, or the actual transfer case control module. This stuff has been around for a while now so you can pick all or some of this up used at a junk yard. But like I said a majority of the ones I've had to mess with ended up being the sensor inside the control motor.