Manual Valve
WARNING: This page is about a different car, the 2007 Hummer H2. However, it is still accessible from the selected car via links, so may be relevant.
Controlled by the selector lever and the manual shaft, the manual valve is in the Park (P) position and directs the line pressure into the PR (Park/Reverse) fluid circuit. Line pressure is blocked from entering any other fluid circuit at the manual valve.