Low/Reverse Clutch
WARNING: This page is about a different car, the 2013 Dodge Avenger and 2013 Chrysler 200. However, it is still accessible from the selected car via links, so may be relevant.
Apply air pressure to the low/reverse clutch feed hole located on the test plate marked LR. Then, listen for an audible thud. The piston should return to its original position after the air pressure is removed.