Jeep 4.0 Automatic not changing gears.

[75sv1]

Try unplugging the TCU. Then shift manually. It will not have kick down. You will need to slow down to down shift. I've always unplugged the TCU and left the fuses intact. If it doesn't work, then I'd say something mechanically wrong with the trans. Check the fluid with the engine not running. It should be up on the 'Z' bends. The start the engine. The fluid level should drop. See if it is down in the 'fill' range. If this doesn't happen, then probably the pump in the trans is not working.