Lock-up System: Notes

The lock-up mechanism of the torque converter clutch operates in all five gears in D, in 3rd gear in D3, and 3rd and 4th gears in S with the automatic shift mode. 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 the hydraulic control, the PCM optimizes the timing and degree of lock-up. When shift solenoid valve D is turned ON by the PCM, shift solenoid valve D pressure switches the lock-up shift valve lock-up ON and OFF. A/T clutch pressure control solenoid valve A and the lock-up control valve control the amount of lock-up.