Lock-up System: Notes

The lock-up mechanism of the torque converter clutch operates in D (2nd, 3rd, 4th, and 5th gears), and in the D3 driving mode (2nd and 3rd gears). 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 the amount of ATF the lock-up mechanism. While shift solenoid valve D is turned on by the PCM, shift solenoid valve D pressure turns the lock-up shift valve receives on and off. A/T clutch pressure control solenoid valve C, the lock-up control valve, and the lock-up timing valve, control the degree of lock-up.