2-3 Shift Valve
WARNING: This page is about a different car, the 2010 Pontiac G5 and 2010 Chevrolet Cobalt. However, it is still accessible from the selected car via links, so may be relevant.
A spring force moves the 2-3 shift valve into the Second gear position when the 2-3 signal fluid exhausts. The D21 fluid continues through the valve and the fluid is also routed into the intermediate band feed fluid circuit. The 3-4 drive fluid, which feeds the direct clutch, exhausts past the 2-3 shift valve.