Workshop Repair and Service Manuals GMC SIERRA
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Automatic Transmission

Tow/Haul Mode      4-Speed Automatic Transmission 6-Speed Automatic Transmission Vehicles with an automatic transmission have a Tow/Haul Mode. The Tow/Haul Mode adjusts the transmission shift pattern to reduce shift cycling,...
Range Selection Mode (Allison® Transmission or Hydra-Matic® 6-Speed Transmission)      The 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....
Low Traction Mode      If your vehicle has the Allison Transmission, or the Hydra-Matic 6-Speed Automatic Transmission, it has a Low Traction Mode that can assist in vehicle acceleration when road conditions are slippery, such as with ice or snow....
Manual Mode     
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...