1-2, 2-3, Reverse Shift Solenoid (SS) Valve Assembly (S3):
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.
Drive (19) fluid passes through orifice #24 into the S3 signal (16) fluid circuit in preparation for a shift. The normally closed 1-2, 2-3, reverse SS valve assembly is energized (ON), allowing any fluid pressure in the S3 signal (16) fluid circuit to exhaust through the solenoid.
IMPORTANT:
Power flow for Intermediate Range - Third Gear is exactly the same as Drive Range - Third Gear.