Grade Logic Control: Ascending Control
When the PCM determines that the vehicle is climbing a hill in the D position, the system extends the engagement area of 2nd and 3rd gears to prevent the transmission from frequently shifting between 2nd and 3rd gears, and between 3rd and 4th gears, so the vehicle can run smooth and have more power when needed. Shift schedules stored in the PCM between 2nd and 3rd gears, and between 3rd and 4th gears, enable it to automatically select the most suitable gear according to the magnitude of a gradient.