Honda 2004 Odyssey Service Manual page 893

Automatic Transmission
System Description (cont'd)
Electronic Control System (cont'd)
Grade Logic Control: Ascending Control
When the PCM determines that the vehicle is climbing a hill in the D and D3 positions, the system extends the
engagement area of 2nd gear, 3rd gear, and 4th gear to prevent the transmission from frequently shifting between
2nd and 3rd gears, between 3rd and 4th gears, and between 4th and 5th gear, so the vehicle can run smooth and have
more power when needed.
NOTE: Shift schedules stored in the PCM between 2nd and 3rd gears, between 3rd and 4th gears, and between 4th and
5th gear, enable to automatically select the most suitable gear according to the magnitude of a gradient.
100 %
50
0
Grade Logic Control: Descending Control
When the PCM determines that the vehicle is going down a hill in the D 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 gear or 4th gear, and you are decelerating while applying the
brakes on a steep hill, the transmission will downshift to lower gear. When you accelerate, the transmission will then
return to higher gear.
100 %
50
0
Grade Logic Control: 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 37 mph (60 km/h), the PCM shifts the transmission from 5th or 4th to 2nd earlier than normal to cope
with upcoming acceleration.
14-280
1ST 2ND 2ND 3RD
62 mph
(100 km/h)
1ST 2ND 2ND 3RD 3RD
62 mph
(100 km/h)
3RD 4TH 4TH 5TH
ASCENDING MODE: Upshift Schedule
: FLAT ROAD MODE
: GRADUAL ASCENDING MODE
: MEDIUM ASCENDING MODE
: STEEP ASCENDING MODE
Vehicle speed
4TH 4TH 5TH
DESCENDING MODE: Downshift Schedule
: FLAT ROAD MODE
: GRADUAL DESCENDING MODE
: MEDIUM DESCENDING MODE
: STEEP DESCENDING MODE
Vehicle speed