Lock up Mechanism

The lock up mechanism operates in the D5 position (2nd, 3rd, 4th, and 5th), and D4 position (2nd, 3rd, and 4th) and D3 position (2nd and 3rd). 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 of the lock up mechanism. When the torque converter clutch solenoid valve activates, modulator pressure changes to switch lock up on and off. The lock up control valve and the lock up timing valve control the range of lock up according to A/T clutch pressure control solenoid valve C. The torque converter clutch solenoid valve is located on the accumulator body in the transmission, and A/T clutch pressure control solenoid valve C is mounted on the transmission housing. They are all controlled by the PCM.