Drive Range, First Gear (Gen 1): Notes
WARNING: This page is about a different car, the 2014 Chevrolet Cruze. However, it is still accessible from the selected car via links, so may be relevant.
As the vehicle speed increases, the transmission control module (TCM) receives input signals from the automatic transmission input and output speed sensors, throttle position sensor and other vehicle sensors to determine the precise moment to deenergize or "turn OFF" the shift solenoid and to command OFF the normally-high R1/456 pressure control solenoid 3.