GMC Sierra Owners Manual
Vehicles with an automatic transmission have a Tow/Haul Mode. The Tow/Haul Mode adjusts the transmission shift pattern to reduce shift cycling, providing increased performance, vehicle control, and transmission cooling when driving down steep hills or Mountain grades, towing, or hauling heavy loads.
The selector button is located on the end of the shift lever. Turn the Tow/ Haul Mode on and off by pressing the button. When the Tow/Haul Mode is enabled, a light on the instrument panel cluster will come on.
See Tow/Haul Mode Light on page 5‑29 and Hill and Mountain Roads on page 9‑13 for more information.
Also see “Tow/Haul Mode” under Towing Equipment on page 9‑100 for more information.
Grade Braking (6-Speed Automatic Transmission)
The Grade Braking shift modes can be activated by pressing the button on the end of the shift control lever.
While in Range Selection Mode, Grade Braking is deactivated allowing the driver to select a desired range of gears.
Grade Braking is only active while the Tow/Haul Mode is selected and you are not in the Range Selection Mode. See “Tow/Haul Mode” listed previously and Manual Mode on page 9‑41 for more information on the Range Selection Mode. Grade Braking assists in maintaining desired vehicle speeds when driving on downhill grades by automatically implementing a shift schedule that utilizes the engine and transmission to slow the vehicle. This reduces wear on the braking system and increases control of the vehicle.
Grade Braking monitors vehicle speed, acceleration, engine torque and brake pedal usage. Using this information, it detects when the truck is on a downhill grade and the driver desires to slow the vehicle by pressing the brake.
This feature is active when the exhaust brake is enabled (if equipped).
Also see Towing Equipment on page 9‑100 for more information.