Shift Pressure Control 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.
The shift pressure control valve regulates drive or reverse (20) fluid pressure into the regulated drive or reverse (21) fluid circuit. Regulated drive or reverse fluid (21) is routed to shift pressure relay valve, enters the B1 control 2 (34) fluid circuit and continues on to the M1 shift valve where it is blocked by the valve in preparation for an upshift to second gear.
IMPORTANT:
Power flow for Intermediate Range - First Gear is exactly the same as Drive Range - First Gear.