2010 Chevrolet Suburban 2500 Owner's Manual - Page 181

Cruise Grade Braking (Hydra-Matic® 6-Speed Automatic Transmission) Cruise Grade Braking assists when driving on a downhill grade. It maintains vehicle speed by automatically implementing a shift schedule that uses the engine and the transmission to slow the vehicle. Cruise Grade Braking operates while Cruise Control is engaged in Tow/Haul mode to assist in maintaining vehicle speed under loaded vehicle conditions. It utilizes vehicle acceleration and deviation from desired speed to determine the correct gear for the operating condition. If vehicle speed is above the desired speed the transmission will downshift to slow the vehicle. If vehicle speed is near or below desired speed the trans will upshift, allowing vehicle speed to increase. While in the Range Select Mode (RSM) mode, Cruise Grade Braking is not available. See Automatic Transmission Operation on page 3‑33. Four-Wheel Drive (Two Speed Automatic Transfer Case) If the vehicle has four-wheel drive, you can send the engine's driving power to all four wheels for extra traction. Read the following before using four-wheel drive. Notice: Driving on clean, dry pavement in Four-Wheel Drive High or Four-Wheel Drive Low for an extended period of time may cause premature wear on the vehicle's powertrain. Do not drive on clean, dry pavement in Four-Wheel Drive High or Four-Wheel Drive Low for extended periods of time. While driving on clean dry pavement and during tight turns, you may experience a vibration in the steering system. The vehicle has StabiliTrak®. Shifting into Four-Wheel-Drive Low will turn Traction Control and StabiliTrak® off. See StabiliTrak® System on page 5‑6. Front Axle The front axle engages and disengages automatically when you shift the transfer case. Some delay for the axle to engage or disengage is normal. 3-41