Drive Range, First Gear (Hydraulic Circuits): Notes
WARNING: This page is about a different car, the 2018 GMC Yukon XL, 2018 GMC Yukon, 2018 Chevrolet Tahoe, 2018 Cadillac Escalade ESV, and 2018 Cadillac Escalade. 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 energize or "turn on". Shift solenoid valve 5 is commanded ON. Shift solenoid valve 4 is already on and commanded for low pressure.