2007 GMC Sierra 1500 Pickup Owner's Manual - Page 147

Tow/Haul Mode The selector button is located on the end of the shift lever. Turn the Tow/Haul on and off by pressing the button. When the Tow/Haul is on, a light on the instrument panel cluster will come on. See Tow/Haul Mode Light on page 264 for more information. If your vehicle has the Performance Package-Enhanced Towing, activating the manual selectable ride will adjust the shock absorber characteristics to enhance the ride and handling of the vehicle for towing or hauling heavy loads. Also see Tow Haul Mode under Towing a Trailer on page 429 for more information. If your vehicle has an automatic transmission, it may have a Tow/Haul mode. If your vehicle has an Allison Transmission® see "Tow/Haul Mode (Allison Transmission®) following. Tow/Haul mode adjusts the transmission shift pattern to reduce shift cycling, providing increased performance, vehicle control, and transmission cooling when towing or hauling heavy loads. 147