Control Valve Body Ball Check Valve - M33 Only
WARNING: This page is about a different car, the 2008 Isuzu Ascender, 2008 GMC Envoy, and 2008 Chevrolet TrailBlazer. However, it is still accessible from the selected car via links, so may be relevant.
Fluid pressure, from the automatic transmission secondary fluid pump assembly, unseats the ball check valve to allow fluid flow to the manual valve, where it is directed to the overrun clutch hydraulic circuit. The check valve prevents fluid, from the main transmission oil pump, from flowing into the secondary fluid pump.