Park - Engine Running

Park - Engine Running
Distribution of Hydraulic Pressure
As the engine turns, the automatic transmission fluid (ATF) pump starts to operate. ATF is drawn through the ATF filter and discharged into the hydraulic circuit. ATF flowing from the ATF pump becomes line pressure that is regulated by the regulator valve. Torque converter pressure, from the regulator valve, enters the torque converter through the lock-up shift valve and is discharged from the torque converter. The torque converter check valve prevents torque converter pressure from rising.

The powertrain control module (PCM) controls the shift solenoid valves ON and OFF. The shift solenoid valves control 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 the automatic transmission clutch pressure control (AT CPC) solenoid valves A and B.

The AT CPC solenoid valves A and B regulate the AT CPC solenoid pressure and apply the AT CPC solenoid pressure to CPC valves A and B. When shifting between upper gear and lower gear, the clutch is engaged by pressure from the CPC pressure mode.

The PCM controls one of the shift solenoid (SS) valves to move the position of the shift valve. This movement switches the port of the CPC and line pressure. Line pressure is then applied to the clutch, and the CPC pressure is intercepted.

When shifting is completed, the clutch is engaged with line pressure.





Hydraulic Pressure at the Ports

P Position
Shift solenoid (SS) valve C is turned OFF by the PCM, and SH C pressure (SC) is applied to the right side of the reverse CPC valve. Then the reverse CPC valve is moved to the left side to uncover the port leading line pressure (3) to the servo valve. Line pressure (3') passes through the servo valve and flows to the manual valve. Line pressure (3") is intercepted at the manual valve, and is not applied to the clutches.

When used, "left" or "right" indicates direction on the hydraulic circuit.





Park - Engine Running