2012 Chevrolet Impala Owner's Manual - Page 209

Driving and Operating 9-25 Manual Mode Electronic Range Select (ERS) Mode The vehicle has an electronic shift position indicator within the instrument cluster. When using the ERS mode a number will display next to the L, indicating the current range that has been selected. To use this feature: 1. Move the shift lever to L (Low). 2. Press the + (Plus) or − (Minus) button located on the left side of the steering wheel, to increase or decrease the gear range available. When you shift from D (Drive) to L (Low), the transmission will shift to a pre-determined lower gear range. The highest gear available for this pre-determined range is displayed next to the L in the DIC. The number displayed in the DIC is the highest gear that the transmission will be allowed to operate in. All gears below that number are available. For example, when 4 (Fourth) is shown next to the L, 1 (First) through 4 (Fourth) gears are automatically shifted by the vehicle. The transmission will not shift into 5 (Fifth) until the + (Plus) button is used or you shift back into D (Drive). While in L (Low), the transmission will prevent shifting to a lower gear range if the engine speed is too high. ERS mode allows you to choose the top-gear limit of the transmission, which can help control the vehicle's speed while driving downhill or towing a trailer.