Distribution of Hydraulic Pressure

As the engine turns, the ATF pump starts to operate. Automatic transmission fluid (ATF) is drawn through the ATF strainer (filter) and discharged into the hydraulic circuit. Then, ATF flowing from the ATF pump becomes line pressure that is regulated by the main regulator valve. Torque converter pressure from the main regulator valve is regulated by the torque converter regulator valve and then flows to the torque converter. The torque converter regulator valve prevents torque converter pressure from rising. Line pressure also becomes torque converter clutch pressure that is regulated by the lock-up control valve, and flows to the torque converter clutch. The PCM switches shift solenoid valves ON and OFF, and it controls the shift solenoid pressure to the shift valves. Applying shift solenoid pressure to the shift valves moves the position of the shift valve, and switches the port of hydraulic pressure. The PCM also controls A/T clutch pressure control solenoid valves A, B, C, and D. The A/T clutch pressure control solenoid valves regulate hydraulic pressure, and applies the pressure to the clutch. When shifting between gears, the clutches are engaged by the A/T clutch pressure control solenoid valve pressures. The PCM actuates the shift solenoid valves to move the position of the shift valves. This movement switches the fluid flow to each clutch. Shifting is completed after the clutch is engaged by the A/T clutch pressure control solenoid valve pressures.