## Automatic Transmission

#### System Description (cont'd)

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Electronic Control System (cont'd)

Grade Logic Control System

Ascending Control

When the PCM determines that the vehicle is climbing a hill in and positions, the system extends the engagement area of 2nd and 3rd gear 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 most suitable gear according to the magnitude of a gradient.

Descending Control

When the PCM determines that the vehicle is going down a hill in and positions, the shift-up speed from 3rd to 4th gear and from 2nd to 3rd (when the throttle is closed) becomes faster than the set speed for flat road driving to widen the 3rd gear and 2nd gear driving areas. This, in combination with engine braking from the deceleration lock-up, achieves smooth driving when the vehicle is descending. There are two descending modes with different 3rd gear driving areas and 2nd gear driving areas to suit the magnitude of the gradients stored in the PCM. When the vehicle is in 4th gear and you are decelerating when you are applying the brakes on a steep hill, the transmission will downshift to 3rd gear. When you accelerate, the transmission will then return to higher gear.

Deceleration Control

When the vehicle goes around a corner and needs to decelerate first and then accelerate, the PCM sets the data for deceleration control to reduce the number of times the transmission shifts. When the vehicle is decelerating from speeds above 27 mph (43 km/h), the PCM shifts the transmission from 4th to 2nd earlier than normal to cope with upcoming acceleration.