Electronic Control System (cont'd)
The PCM turns the shift solenoid valves A, B, C, D, and E ON and OFF to control shifting transmission gear. The combination of driving signals to shift solenoid valves A, B, C, D, and E are shown in table.

Position | Gear position | Shift solenoid valves
--- | --- | ---
A | B | C | D | E
D, D3, M | Shifting from N position | OFF | ON | ON | OFF | OFF
Stays in 1st | ON | ON | ON | OFF | OFF
Shifting gears between 1st and 2nd | OFF | ON | ON | OFF | OFF
Stays in 2nd | OFF | ON | OFF | ON | OFF or ON
Shifting gears between 2nd and 3rd | OFF | ON | ON | ON | OFF or ON
Stays in 3rd | OFF | OFF | ON | OFF | OFF or ON
D, M | Shifting gears between 3rd and 4th | OFF | OFF | OFF | OFF | OFF or ON
Stays in 4th | ON | OFF | OFF | OFF | OFF or ON
Shifting gears between 4th and 5th | ON | OFF | OFF | ON | OFF or ON
Stays in 5th | ON | OFF | ON | ON | OFF or ON
R | Shifting from P and N position | OFF | ON | OFF | OFF | ON
Stays in reverse | ON | ON | OFF | OFF | ON
Reverse inhibit | ON | ON | OFF | OFF | OFF
P | Park | OFF | ON | OFF | OFF | ON
N | Neutral | OFF | ON | ON | OFF | OFF

Grade Logic Control: Ascending Control
When the PCM determines that the vehicle is climbing a hill in D and D3 positions, the system extends the engagement area of 2nd, 3rd, and 4th gears to prevent the transmission from frequently shifting between 2nd and 3rd gears, between 3rd and 4th gears, and between 4th and 5th gears, so the vehicle can run smooth and have more power when needed.
Shift schedules stored in the PCM between 2nd and 3rd gears, between 3rd and 4th gears, and between 4th and 5th gears, enable it to automatically select the most suitable gear according to the magnitude of a gradient.
Grade Logic Control: Descending Control
When the PCM determines that the vehicle is going down a hill in D and D3 positions, the shift-up speed from 4th to 5th gear, from 3rd to 4th gear, and from 2nd to 3rd gear (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 area. 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 when you are applying the brakes on a steep hill, the transmission will downshift to lower gear. When you accelerate, the transmission will then return to a higher gear.