U1 Shift Valve
WARNING: This page is about a different car, the 2003 Saturn Vue. However, it is still accessible from the selected car via links, so may be relevant.
PN12345 (47) fluid is routed to the U1 shift valve where it is blocked by the valve in preparation for an upshift to third gear.
IMPORTANT:
Power flow for Intermediate and Low Range - Second Gear is exactly the same as Drive Range - Second Gear.