2007 GMC Sierra 1500 Pickup Owner's Manual - Page 149

Cruise Grade Braking is available on the 6.6L DURAMAX® diesel engine. Cruise Grade Braking monitors a vehicle's cruise state, engine torque, acceleration, vehicle speed, and the cruise set speed. Using this information, it detects when the truck is accelerating on a downhill grade and will automatically downshift to slow the vehicle if it exceeds the cruise set speed by a certain amount. See Cruise Control on page 217 for more information. The Tow/Haul mode and Grade Braking shift modes can be activated by pressing the button on the end of the shift control stalk. If your vehicle has the DURAMAX® diesel Engine or the 8.1L VORTEC™ gasoline engine, Grade Braking is only available while the Tow/Haul Mode is selected. While in the Range Selection Mode, Grade Braking is deactivated allowing the driver to select a desired range of gears. See Automatic Transmission Operation on page 140 for more information. Also see Towing a Trailer on page 429 for more information. Manual Transmission Operation Five-Speed (VORTEC™ 6.0L V8 Engine) Here is how to operate your transmission. FIRST (1) is intended only for heavy loads or trailer towing and is not recommended for normal driving. During the first 500 miles (805 km) of vehicle use, start your vehicle moving in FIRST (1). This allows clutch components to break-in properly. 149