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Home >> Acura >> 2003 >> MDX Base >> Repair and Diagnosis >> Transmission >> Automatic Trans >> Automatic Transmission >> System Description >> Electronic Control System >> Descending Control
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Descending Control

When the PCM determines that the vehicle is going down a hill in the D5, D4, and D3 positions, the shift-up speed from 4th to 5th gear, 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 4th gear, 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 three descending modes with different 4th gear driving areas, 3rd gear driving areas and 2nd gear driving areas according to the magnitude of a gradient stored in the PCM. When the vehicle is in 5th or 4th gear and you are decelerating while applying the brakes on a steep hill, the transmission will downshift to a lower gear. When you accelerate, the transmission will then return to a higher gear.

Fig 1: Identifying Descending Control Graph
G03640161Courtesy of AMERICAN HONDA MOTOR CO., INC.