2008 GMC Sierra 1500 Pickup Owner's Manual - Page 106

Range Selection Mode When in the MANUAL MODE (M) a number displays next to the M, indicating the current gear that has been selected. The number displayed in the gear indicator is the highest gear that can be used. However, your vehicle can automatically shift to lower gears as it adjusts to driving conditions. This means that all gears below that number are available. When FIFTH (5) is selected, FIRST (1) through FIFTH (5) gears are automatically shifted by the vehicle, but SIXTH (6) cannot be used until the plus/minus button located on the steering column lever is used to change to the gear. The Range Selection Mode controls the vehicle and engine speed while driving down a hill or towing a trailer, by allowing you to select a desired range of gears. Grade Braking is not available when the Range Selection Mode is active. See Tow/Haul Mode on page 2-31 for more information. On vehicles with a Range Selection Mode. The Range Selection Mode controls the vehicle's transmission. To use this feature, do the following: 1. Move the shift lever to the MANUAL MODE (M). 2. Press the plus/minus button, to upshift or downshift selecting the desired range of gears for your current driving conditions. While using the Range Selection Mode, Cruise Control and the Tow/Haul mode can be used. 2-30