2008 GMC Yukon Owner's Manual - Page 133

MANUAL MODE (M): This position, is available on vehicles with the Allison Transmission® or Hydra-Matic® 6-Speed transmission. It lets drivers select the range of gears appropriate for current driving conditions. If your vehicle has this feature, see Range Select Mode (Allison Transmission® or Hydra-Matic® 6-Speed transmission) later in this section. THIRD (3): This position is also used for normal driving. It reduces vehicle speed more than DRIVE (D) without using the brakes. You might choose THIRD (3) instead of DRIVE (D) when driving on hilly, winding roads, when towing a trailer, so there is less shifting between gears and when going down a steep hill. SECOND (2): This position reduces vehicle speed even more than THIRD (3) without using your brakes. You can use SECOND (2) on hills. It can help control your speed as you go down steep mountain roads, but then you would also want to use the brakes off and on. If you manually select SECOND (2) in an automatic transmission, the transmission will start in second gear. You can use this feature for reducing the speed of the rear wheels when you are trying to start your vehicle from a stop on slippery road surfaces. FIRST (1): For the Hydra-Matic® 4-Speed transmission this position reduces vehicle speed even more than SECOND (2) without using the brakes. You can use it on very steep hills, or in deep snow or mud. If the shift lever is put in FIRST (1) while the vehicle is moving forward, the transmission does not shift into first gear until the vehicle is going slowly enough. For an Allison Transmission® or Hydra-Matic® 6-Speed transmission, this position reduces vehicle speed without using your brakes. You can use it for major/severe downgrades and off-road driving where the vehicle would otherwise accelerate due to steepness of grade. When you shift to FIRST (1) it provides the lowest gear appropriate to your current road speed and continues to downshift as the vehicle slows, eventually downshifting to FIRST (1) gear. 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. 2-35