2008 GMC Yukon Owner's Manual - Page 134

Range Selection Mode (Allison® or Hydra-Matic® 6-Speed Transmission) When MANUAL MODE (M) is selected a number displays next to the M, indicating the current gear. This number 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. Grade Braking is not available when the Range Selection Mode is active. See Tow/Haul Mode on page 2-37. While using the Range Selection mode feature, cruise control and the Tow/Haul mode can be used. Your vehicle may have a Range Selection Mode. The Range Selection Mode helps control the vehicle's transmission and vehicle speed while driving down hill or towing a trailer by letting you select a desired range of gears. To use this feature, do the following: 1. Move the shift lever to the MANUAL MODE (M). 2. Press the plus/minus buttons, located on the steering column shift lever, to select the desired range of gears for your current driving conditions. 2-36 Notice: Spinning the tires or holding the vehicle in one place on a hill using only the accelerator pedal may damage the transmission. The repair will not be covered by your warranty. If you are stuck, do not spin the tires. When stopping on a hill, use the brakes to hold the vehicle in place.