Lock-Up Control

LOCK-UP CONTROL

Lock-up "OFF"
- When the "lock-up" is released, the torque converter clutch control valve is moved downward by both oil pump discharge pressure and spring force. Torque converter relief pressure then flows through oil passages (3) and (5), and is directed to the oil cooler via the torque converter and oil passages (4) and (9). Since "release" pressure within the torque converter is equal to or greater than the "apply" pressure, the "lock-up" is released.
- The following pressures attempt to move the 4th speed cut valve downward via oil passage (10).
a. Torque converter clutch solenoid pressure [when throttle is fully closed (idle switch is in "ON" position)]
b. Line pressure (when the selector lever is set to the "2" or "1" position)
c. Kickdown modifier pressure (when kickdown occurs)
- As the 4th speed cut valve is moved downward, the "lock-up" .15 released.

Lock-up "ON" (D4)
- The "lock-up" is applied when the specified vehicle speed is exceeded.
- When the specified vehicle speed is exceeded while driving in the D4 position, governor pressure attempts to move the 4th speed cut valve upward. As the valve moves upward, oil passage (6) is opened to oil passage (7). 3-4 shift valve output pressure (line pressure) is then applied to the lower end of the torque converter clutch control valve. The torque converter clutch control valve then moves upward to close oil passages (3) and (5) and to open oil passage (5) to drain oil passage (8).
- Torque converter relief pressure, which was applied to the lock-up "release" side, passes through oil passages (3) and (4), and is applied to the torque converter. Since the "release" pressure is then drained, the "lock-up" is applied.

Torque converter clutch solenoid valve operation
- The torque converter clutch solenoid valve is installed on the control valve body.
- The torque converter clutch solenoid valve is connected to the ECM and is controlled by an ON or OFF signal sent from the idle switch (throttle sensor).
1. Throttle (opening) position is less than 1/8:
- The idle switch turns "ON" to send an ON signal to the ECM. The ECM then turns the torque converter clutch solenoid valve "ON".
- This causes torque converter clutch solenoid valve pressure (line pressure) to pass through oil passage (10) and act on the 4th speed cut valve. Both the 4th speed cut valve and torque converter clutch control valve function in the same way as in the lock-up "release" state.
2. Throttle opening is more than 1/8:
- As the idle switch is turned "OFF", the torque converter clutch solenoid valve is also "OFF".
- Both the 4th speed cut valve and torque converter clutch control valve function in the same way as in the lock-up "apply" state.