Lock-Up Control

DESCRIPTION
The lock-up engaging and disengaging conditions are set for each gear shift range, gear position and shift pattern and correspond to the throttle position and vehicle speed, and the duty solenoid is electronically controlled by TCM controls the lock-up clutch. The lock-up clutch engagement and disengagement are controlled by the lock-up control valve.

When Engaging And Disengaging
The shuttle shift valve D is actuated by the hydraulic pressure from the shift valve A. It controls the position of the lock-up control valve for engaging or disengaging the lock-up clutch.

NON-LOCK-UP OPERATION (1ST, N, R, AND P RANGE)
Since no operating pressure is generated from the shift valve A, the shuttle shift valve D sets the lock-up control valve in the "disengaging" position.

The lock-up operating pressure (torque converter clutch regulator pressure) acts on the lock-up clutch disengaging circuit, while the engaging circuit communicates with the oil cooler circuit. Accordingly, the lock-up clutch is disengaged by the pressure difference.

LOCK-UP OPERATION (4TH SPEED OF D RANGE)
The operating pressure generated by the shift valve A is applied to the shuttle shift valve D, which pushes the lock-up control valve to the "engaging" position. Since the lock-up operating pressure is applied to the engaging side circuit while the disengaging circuit is drained, the lock-up clutch is engaged by the pressure difference.

Smooth Control
The duty solenoid B is controlled by the TCM and controls the operation of the lock-up control valve. Because the lock-up operating pressure is controlled by the lock-up control valve, the force applied to the lock-up clutch is controlled for smooth clutch operation.

When locking up, the clutch is set in the half-engaged state beforehand. After this, the lock-up operating pressure is gradually increased to achieve smooth locking up.