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7A1-30 CONSTRUCTION AND FUNCTION
LINE PRESSURE CONTROL • Either the throttle opening, vehicle speed, turbine rotational speed, ATF temperature or speed-change range signal appropriate under the situation is issued from the TCM. The ON/OFF type line pressure • The line pressure generated by the oil pump acts on the point A of the pressure regulator valve. When the pressure control solenoid is turned ON by the signal from the TCM, the solenoid pressure does not • When the pressure control solenoid is turned OFF, the solenoid pressure acts so that the line pressure is adjusted to match the spring force acting on the right side of the pressure regulator valve. • As a result, the line pressure is adjusted to be low when the pressure control solenoid is ON and to be high when the pressure control solenoid is OFF. • In the D, 3, 2 and L range, the line pressure through the oil pressure circuit acts onto the point B of the pressure regulator valve and the pressure regulator valve moves so as to increase the pressure to be
Figure 50. Line Pressure Control
LOCK-UP CONTROL • The lock-up solenoid adjusts the pressure and controls the lock-up based on the pre-set lock-up point, according to the vehicle speed, throttle opening, engine rotations, turbine rotations and ATF temperature • Smooth lock-up control is employed to engage or disengage the clutch smoothly at the time of lock-up. • When the oil temperature is low (below 20 ° C) or high (over 128 ° C), lock-up is disengaged even though the vehicle is at the lock-up speed. • The lock-up is disengaged also when the throttle is closed. • When the TCM determines the lock-up engagement, the DUTY ratio to supply power to the lock-up solenoid is gradually increased (5% to 95%) and the oil between the lock-up piston and converter cover is drained.
As a result, the lock-up piston is fitted slowly under pressure to the converter cover securing smooth lock-
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