Lost speed on the freeway when 4x4 low light came on and could not switch back to 4x4 auto. happened twice in a two week period. Dealership checked out after the first incident and said it was a weak battery which after replacing battery (was original) 4x4 reset and no problem for a couple of weeks. Also while trying to get to the exit (approximately 2 miles away) became increasingly difficult to achieve speed and eventually locked up and could not move forward or backward. Towed home and let sit for 1 1/2 weeks started up today and was able to move, drove around a couple of blocks seemed to be sluggish and whining to achieve gear change, when backing in to driveway could feel system dragging. Was told it possibly could be a sensor. Can't seem to find any info on a transmission sensor problem.