Hill Start Assist Control (HAC) is designed to help minimize backward rolling on steep ascents. Downhill Assist Control (DAC) is designed to help the driver maintain vehicle control and speed on steep, downhill descents. Neither system is a substitute for safe driving judgment and practices. Factors including speed, grade, surface conditions and driver input can all affect whether DAC and HAC will be effective in preventing a loss of control. Please see your Owner's Manual for further details.