I had this happen on my 99. what i did was remove that electical motor and put the transfer case back into 2hi with a pair of pliers then I took a battery and hooked it up to the power wires for the motor till it was back to the 2wd position and then bolted the motor back on. what I think happened was the sensor that tells it when its in 4low must not be working. as long as i dont use 4low i dont have any problems.