Fig. 27: Grade Logic Control - Ascending Control Graph
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Grade Logic Control: Descending Control
When the PCM determines that the vehicle is going down a hill in D, 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 extend the 4th
gear, 3rd gear, and 2nd gear engagement 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. 28: Grade Logic Control - Descending Control Graph
2008 Honda Civic LX
2006-08 TRANSMISSION Automatic Transmission - Civic (Except Hybrid)