Lock-up Mechanism

The lock-up mechanism operates in all five gears in D, in 3rd gear in D3, and in 3rd and 4th gears in S. The pressurized fluid is drained from the back of the torque converter through a fluid passage, causing the torque converter clutch piston to be held against the torque converter cover. As this takes place, the mainshaft rotates at the same speed as the engine crankshaft. Together with hydraulic control, the PCM optimizes the timing and degree of the lock-up mechanism. While shift solenoid valve D is turned on and off by the PCM, shift solenoid valve D pressure switches the lock-up shift valve on and off. A/T clutch pressure control solenoid valve A and the lock-up control valve control the degree of the lock-up.