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Shift Control
Shifting is related to engine torque through the solenoid valves, which are controlled by the PCM. The PCM instantly
determines which gear should be selected by various signals sent from sensors, and actuates the shift solenoid valves
A, B, and C to control shifting. Also, a grade logic control system has been adopted to control shifting in the D4 and D3
positions while the vehicle is ascending or descending a slope, or reducing speed.
The combination of driving signals to shift solenoid valves A, B, and C are shown in the table.
Position
D4, D3
Shifting from the N position
Stays in 1st
Shifting gears between 1st and 2nd
Stays in 2nd
Shifting gears between 2nd and 3rd
Stays in 3rd
D4
Shifting gears between 3rd and 4th
Stays in 4th
2
2nd
1
1st
R
Shifting from the P and N position
Stays in reverse
Reverse inhibit
P
Park
N
Neutral
Lock-up Control
The torque converter clutch solenoid valve controls modulator pressure to switch the lock-up shift valve and lock-up
ON and OFF. The PCM controls the torque converter clutch solenoid valve and the A/T clutch pressure control solenoid
valves A and B. When the torque converter clutch solenoid valve is turned ON, the condition of lock-up starts. The A/T
clutch pressure control solenoid valves A and B regulate A/T clutch pressure control solenoid pressure and apply the
pressure to the lock-up control valve and the lock-up timing valve. The lock-up control mechanism operates in 3rd and
4th gear in D4, and in 3rd gear in D3 positions.
Gear position
Shift solenoid valves
A
B
ON
ON
OFF
ON
ON
ON
ON
ON
ON
OFF
ON
OFF
OFF
OFF
OFF
OFF
ON
ON
OFF
ON
OFF
ON
OFF
ON
OFF
ON
OFF
ON
OFF
ON
C
ON
ON
ON
OFF
OFF
ON
ON
OFF
OFF
ON
ON
OFF
ON
OFF
OFF
(cont'd)
14-31
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