GMC Sierra Owners Manual
Using Cruise Control on Hills
How well the cruise control works on hills depends on the vehicle speed, the load, and the steepness of the hills. When going up steep hills, pressing the accelerator pedal may be necessary to maintain vehicle speed.
While going downhill:
• Vehicles with a four speed automatic transmission may need to have the brakes applied or the transmission shifted to a lower gear to keep the speed down.
• Vehicles with a six speed automatic transmission have a Cruise Grade Braking feature that may automatically shift to a lower gear to keep the speed down. It may be necessary to apply the brake or manually shift the transmission to a lower gear.
The vehicle may shift to a higher gear when grade braking assistance is no longer required.
Cruise Grade Braking is not available while in Range Selection Mode. This feature is active when the exhaust brake is enabled (if equipped). See "Range Selection Mode" under Manual Mode on page 9‑41.
When the brakes are manually applied the cruise control is disengaged.