Electronic Control System (cont'd)
The PCM turns shift solenoid valves A, B, C, D, and E ON and OFF to control gear selection. The combination of driving signals to shift solenoid valves A, B, C, D, and E are shown in the table.
Position
Gear Position
Shift Solenoid Valve
A
B
C
D
E
D and S
Shifting from N
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
Shifting gears between 3rd and 4th
OFF
OFF
OFF
OFF
OFF or ON
Stays in 4th
ON
OFF
OFF
OFF
OFF or ON
D
Shifting gears between 4th and 5th
ON
OFF
OFF
ON
OFF or ON
Stays in 5th
ON
OFF
ON
ON
OFF or ON
N
Neutral
OFF
ON
ON
OFF
OFF
R
Shifting from P and N
OFF
ON
OFF
OFF
ON
Stays in reverse
ON
ON
OFF
OFF
ON
Reverse inhibit control
OFF
OFF
ON
OFF
OFF
P
Park
OFF
ON
OFF
OFF
ON


Grade Logic Control: Ascending Control

When the PCM determines that the vehicle is climbing a hill in D, 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. The PCM does this so the vehicle can run smooth and have more power when needed.
Shift programs 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, the upshift 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 extend 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.