AT2–6 A340E (2JZ—GTE) AUTOMATIC TRANSMISSION – OPERATION HYDRAULIC CONTROL SYSTEM The hydraulic control system is composed of an oil pump, valve body, solenoid valves, accumulators, clutches and brakes, as well as the fluid passages which connect all of these components. Based on the hydraulic pressure created by the oil pump, the hydraulic control system governs the hydraulic pressure acting on the torque converter clutch, clutches and brakes in accordance with the vehicle driving conditions. There are five solenoid valves on the valve body. The No.1 and No.2 solenoid valves are turned on and off by signals from the ECM to control the shift valves, and change the gear shift position. The No.3 solenoid valve is operated by signals from the ECM to engage or disengage the lock–up clutch of the torque converter clutch. The No.4 solenoid valve is operated by signals from the ECM to control the engagement speed and reduce gear shift shock. The No.5 solenoid valve is operated by signals from the ECM to regulate the line pressure to throttle pressure. HYDRAULIC CONTROL SYSTEM VALVE BODY OIL PUMP Hydr. pressure control Fluid passage switching CLUTCHES & BRAKES Planetary gear sets Torque Converter Clutch ECM SOLENOID VALVES V03090