Grade Logic Control: Descending Control

When the PCM determines that the vehicle is going down a hill in D, and in S with automatic shift mode, the upshift speed from 5th to 6th gear, from 4th to 5th gear, and from 3rd to 4th gear (when the throttle is closed) becomes higher than the set speed for flat road driving to extend the 5th gear, 4th gear, and 3rd gear driving areas. This, in combination with engine braking from the deceleration lock-up, achieves smooth driving when the vehicle is descending. There are descending modes with different 5th gear, 4th gear, and 3rd gear driving areas based on the steepness of the grade stored in the PCM. When the vehicle is in 6th, 5th, or 4th gear, and the vehicle is decelerating while applying the brakes on a steep hill, the transmission downshifts to a lower gear. When you accelerate, the transmission then returns to a higher gear from the current position.