Shift Pressure Relay Valve
WARNING: This page is about a different car, the 2009 Pontiac Torrent and 2009 Chevrolet Equinox. However, it is still accessible from the selected car via links, so may be relevant.
S5 signal (18) fluid is routed to the shift pressure relay valve and applies the valve against spring force.
Exhausting direct clutch feed 1 (27) fluid passes through the shift pressure relay valve and enters the regulated drive or reverse (21) circuit.