04 chevy 2500 duramax. I had it out on a two track this morning while hunting, got into some sand so I engaged the 4x4. All was good until I went up an incline and the RPMS reved Up a bit and I had no forward power. No I let off the gas and pushed the 2wd button. The truck then moved up the hill however sluggishly. I then realized that the truck was still in 4wd even though I selected 2wd. Got out to the main rd and basically now the truck is stuck in 4wd and I only have 2nd gear and reverse. (This is limp mode from my understanding). I’ve looked things over but have no idea. Is it possible the tcase encoder went bad and that caused the truck to go into limp mode?