Overdrive Range, Fourth Gear - Torque Converter Clutch Applied: Notes
WARNING: This page is about a different car, the 2009 GMC Yukon and 2009 Chevrolet Tahoe. However, it is still accessible from the selected car via links, so may be relevant.
At higher vehicle speeds, the Hydra-matic 4L60-E transmission uses an overdrive gear ratio (fourth gear) in order to increase fuel economy and in order to maximize engine performance. When vehicle operating conditions are appropriate, the PCM energizes the 1-2 shift solenoid valve to shift the transmission into fourth gear.