A/T System Description - Hydraulic Flow (A/T)
A/T System Description - Hydraulic Flow
Hydraulic Flow
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 regulator valve. Torque converter pressure from the regulator valve enters the torque converter through the lock-up shift valve, and it is discharged from the torque converter. The torque converter check valve prevents torque converter pressure from rising.
The PCM switches the shift solenoid valves ON and OFF. The shift solenoid valve controls line pressure from the ATF pump via the manual valve when the shift solenoid valve is OFF. When the shift solenoid valve is turned ON by the PCM, line pressure changes to shift solenoid valve pressure at the shift solenoid valve, then the shift solenoid valve pressure flows to the shift valve. Applying shift solenoid pressure to the shift valve moves the position of the shift valve, and switches the port of the hydraulic circuit. The PCM also controls A/T clutch pressure control solenoid valves A, B, and C. The A/T clutch pressure control solenoid valves regulate hydraulic pressure, and apply the pressure to the clutches to engage smoothly. The clutches receive optimum clutch pressure which is regulated by the A/T clutch pressure control solenoid valves for comfortable driving and shifting under all conditions.
Hydraulic Pressure at the Port for use in the hydraulic circuit
Hydraulic Flow (cont'd)
N Position
The PCM controls the shift solenoid valves. The conditions of the shift solenoid valves and positions of the shift valve are as follows:
- Shift solenoid valve A is turned OFF, shift valve A remains on the right side, and cut valve A remains on the left side.
- Shift solenoid valve B is turned OFF, and shift valve B remains on the right side.
- Shift solenoid valve C is turned OFF, and shift valve C remains on the right side.
Line pressure (1) passes through the manual valve and stops at cut valve B. Line pressure (1) also flows to shift solenoid valves, and A/T clutch pressure control solenoid valve A. Under this condition, hydraulic pressure is not applied to the clutches.
NOTE: When used, "left" or "right" indicates direction on the hydraulic circuit.
D Position: 1st gear shifting from the N position
The shift solenoid valves and the shift valves remain the same position when shifting from D to N. The PCM actuates A/T clutch pressure control solenoid valve A to regulate the line pressure. Line pressure (1) becomes A/T clutch pressure control solenoid valve A pressure (55), and A/T clutch pressure control solenoid valve A pressure flows to the lock-up shift valve, shift valve B, the manual valve, and shift valve A. Also solenoid valve A pressure becomes 1st clutch pressure (10) at shift valve C, and 1st clutch pressure (10) flows to the 1st clutch. The 1st clutch is engaged by A/T clutch pressure control solenoid valve A pressure mode when shifting to D from N.
NOTE: When used, "left" or "right" indicates direction on the hydraulic circuit.
Hydraulic Flow (cont'd)
D Position: Driving in 1st gear
The PCM turns shift solenoid valve B ON, and shift solenoid valves A and C remain OFF. Shift solenoid valve B pressure (SB) is applied to the right side of shift valve B. Shift valve B then moves to the left side, causing the line pressure port leading to the 1st clutch to be uncovered, and the A/T clutch pressure control solenoid valve A pressure port to be covered. Line pressure (1B) passed through shift valve B flows to the manual valve, shift valve A, and shift valve C, and becomes 1st clutch pressure (10). 1st clutch pressure is applied to the 1st clutch, and the 1st clutch is engaged by the line pressure mode.
NOTE: When used, "left" or "right" indicates direction on the hydraulic circuit.
D Position: Shifting between 1st gear and 2nd gear
As the speed of the vehicle reaches the programmed value, the PCM turns shift solenoid valve A ON, shift solenoid valve B remains ON, and C remains OFF. Shift solenoid valve A pressure (SA) is applied to the right end of shift valve A and to the left side of cut valve A. Cut valve A is moved to the right side to release 1st clutch pressure in line pressure mode, and shift valve A is moved to the left side to switch line pressure (5A) port to A/T clutch pressure control solenoid valve C pressure (5C) port leading to the 1st clutch. Also shift valve A uncovers 2nd clutch pressure (20) port leading A/T clutch pressure control solenoid valve B pressure (56) to the 2nd clutch. The 1st clutch and the 2nd clutch are engaged by the A/T clutch pressure control solenoid valve pressure mode.
NOTE: When used, "left" or "right" indicates direction on the hydraulic circuit.
Hydraulic Flow (cont'd)
D Position: Driving in 2nd gear
The PCM turns shift solenoid valve B OFF, shift solenoid valve A remains ON, and C remains OFF. Shift solenoid valve B is turned OFF, and shift solenoid valve B pressure (SB) in the right end of shift valve B and in the left end of the servo control valve is released. Cut valve B and servo control valve are kept in the right side by line pressure (4) even though releasing hydraulic pressure in the left end. Shift valve B is moved to the right side to switch A/T clutch pressure control solenoid valve B pressure (5F) port to line pressure (5D) port leading to the 2nd clutch. 2nd clutch pressure (20) is applied to the 2nd clutch, and the 2nd clutch is engaged by the line pressure mode.
NOTE: When used, "left" or "right" indicates direction on the hydraulic circuit.
D Position: Shifting between 2nd gear and 3rd gear
As the speed of the vehicle reaches the programmed value, the PCM turns shift solenoid valve A OFF, while shift solenoid valve B and C remain OFF. Shift solenoid valve A is turned OFF, and shift solenoid valve A pressure (SA) in the right end of shift valve A and in the left end of cut valve A is released. Even though shift solenoid valve A pressure is released, cut valve A is kept on the right side by line pressure (4). Shift valve A is moved to the right side to switch to the line pressure (5G) port to the A/T clutch pressure control solenoid valve B pressure (5E) port leading to the 2nd clutch. Also shift valve A uncovers 3rd clutch pressure (30) port leading A/T clutch pressure control solenoid valve C pressure (5L) to the 3rd clutch. The 2nd and 3rd clutch are engaged by the A/T clutch pressure control solenoid valve pressure mode.
NOTE: When used, "left" or "right" indicates direction on the hydraulic circuit.
Hydraulic Flow (cont'd)
D Position: Driving in 3rd gear
The PCM turns shift solenoid valve C ON, and shift solenoid valve A and B remain OFF. Shift solenoid valve C pressure (SC) is applied to the right side of shift valve C and cut valve B. Shift valve C is then moved to the left side to releasing the 2nd clutch pressure. The 3rd clutch keeps on engaging with the A/T clutch pressure control solenoid valve C pressure mode.
NOTE: When used, "left" or "right" indicates direction on the hydraulic circuit.
D Position: Shifting between 3rd gear and 4th gear
As the speed of the vehicle reaches the programmed value, the PCM turns shift solenoid valve A ON. Shift solenoid valve B remains OFF, and C remains ON. Shift solenoid valve A pressure (SA) is applied to the right end of shift valve A and the left end of cut valve A. Shift valve A is moved to the left side, switching the line pressure (5L) port to the A/T clutch pressure control solenoid valve C pressure (5K) port leading to the 3rd clutch. Also shift valve A uncovers the 4th clutch pressure (40) port leading A/T clutch pressure control solenoid valve B pressure (5H) to the 4th clutch. The 3rd and 4th clutches are engaged by the A/T clutch pressure control solenoid valve pressure mode.
NOTE: When used, "left" or "right" indicates direction on the hydraulic circuit.
Hydraulic Flow (cont'd)
D Position: Driving in 4th gear
The PCM turns shift solenoid valve B ON, and shift solenoid valve A and B remain ON. Shift solenoid valve B pressure (SB) is applied to the right side of shift valve B and the left side of the servo control valve. Shift valve B then moves to the left side releasing the 3rd clutch pressure. The 4th clutch is engaged by the A/T clutch pressure control solenoid valve B pressure mode.
NOTE: When used, "left" or "right" indicates direction on the hydraulic circuit.
D Position: Shifting between 4th gear and 5th gear
As the speed of the vehicle reaches the programmed value, the PCM turns shift solenoid valve A OFF while shift solenoid valve B and C remain ON. As a result, the pressure in the right end of shift valve A is released. Even though shift solenoid valve A pressure (SA) is released, cut valve A is kept on the right side by the line pressure (4). Shift valve A is moved to the right side to uncover A/T clutch pressure control solenoid valve C pressure (5T) (5J) port leading to the 4th clutch. The 4th and 5th clutches are engaged by the A/T clutch pressure control solenoid valve pressure mode.
NOTE: When used, "left" or "right" indicates direction on the hydraulic circuit.
Hydraulic Flow (cont'd)
D Position: Driving in 5th gear
The PCM turns shift solenoid valve C OFF, shift solenoid valve A remains OFF, and B remains ON. Shift solenoid valve C pressure (SC) is then released to the right side of shift valve C. This causes shift valve C to move to the right side, releasing the 4th clutch pressure. The 5th clutch is engaged by the A/T clutch pressure control solenoid valve C pressure mode.
NOTE: When used, "left" or "right" indicates direction on the hydraulic circuit.
2 Position
The PCM controls the shift solenoid valves and the A/T clutch pressure control solenoid valves. The conditions of the shift solenoid valves and the position of the shift valves are as follows:
- Shift solenoid valve A is turned ON, causing shift valve A to move to the left side.
- Shift solenoid valve B is turned OFF, keeping shift valve B on the right side.
- Shift solenoid valve C is turned OFF, keeping shift valve C on the left side.
Line pressure travels up and through shift valve C (5D), through shift valve B (5G), and then up to shift valve A (20) to become 2nd clutch pressure. The 2nd clutch is engages by the 2nd clutch pressure.
NOTE: When used, "left" or "right" indicates direction on the hydraulic circuit.
Hydraulic Flow (cont'd)
1 Position
The PCM controls the shift solenoid valves and the A/T clutch pressure control solenoid valves. The conditions of the shift solenoid valves and the position of the shift valves are as follows:
- Shift solenoid valve A is turned OFF, keeping shift valve A on the right side.
- Shift solenoid valve B is turned ON, causing shift valve B move to the left side.
- Shift solenoid valve C is turned OFF, keeping shift valve C on the right side.
Line pressure (1) from the manual valve flows to cut valve B, cut valve A, shift valve B, and becomes line pressure (5A) at the manual valve. Line pressure (5A) passes through shift valve A, flows to shift valve C, and becomes 1st clutch pressure (10). 1st clutch pressure (10) is applied to the 1st clutch, and the 1st clutch is engaged.
NOTE: When used, "left" or "right" indicates direction on the hydraulic circuit.
R Position: Shifting to the R position from the P or N position
The manual valve is moved into the R position. This causes line pressure (1) to become line pressure (1), (3), and (7) at the manual valve. The PCM turns shift solenoid valves C and D ON, and shift solenoid valves A and B remain OFF. Shift solenoid valve D pressure (SD) is applied to the left end of shift valve D, causing shift valve D to move to the right side, uncovering the line pressure (3) port leading to the servo valve. Line pressure (3') from shift valve D flows to the servo valve, and pushes the servo valve to the reverse position. The PCM controls A/T clutch pressure control solenoid valve A to regulate A/T clutch pressure control solenoid valve A pressure (55), and A/T clutch pressure control solenoid valve A pressure (55) flows to the lock-up shift valve, shift valve B, the manual valve, the servo valve, shift valve D, and cut valve A. A/T clutch pressure control solenoid valve A pressure (3C) becomes 5th clutch pressure (50) at cut valve A. 5th clutch pressure (50) is applied to the 5th clutch, and the 5th clutch is engaged by the A/T clutch pressure control solenoid valve A pressure mode.
NOTE: When used, "left" or "right" indicates direction on the hydraulic circuit.
Hydraulic Flow (cont'd)
R Position: Driving in reverse gear
When starting off in reverse gear, the PCM turns shift solenoid valves B and C ON. Shift solenoid valve A remains OFF, and D remains ON. Shift solenoid valve B is turned ON, and shift solenoid valve B pressure (SB) is applied to the right end of shift valve B. Shift valve B is moved to the right side to switch A/T clutch pressure control solenoid valve A pressure (55') port to line pressure (1B) port leading to the 5th clutch. The 5th clutch is engaged with the line pressure mode.
Reverse Inhibitor Control
When R is selected while the vehicle is moving forward at speeds over 6 mph (10 km/h), the PCM commands shift solenoid valves A and C ON, and shift solenoid valves B and D OFF. Shift solenoid valve D is kept OFF, and shift valve D is kept in the left side to cover line pressure (3) port leading to the servo valve. The servo valve is kept in the forward position. Shift solenoid valve A is turned ON, shift valve A is moved to the right side and covers the port to stop line pressure (1A) leading to the 5th clutch. The servo valve is not applied line pressure, the 5th clutch is not applied 5th clutch pressure, as a result, power is not transmitted to the reverse direction.
NOTE: When used, "left" or "right" indicates direction on the hydraulic circuit.
P Position
The manual valve is moved into the P position, line pressure (1) becomes line pressure (1), (3), and (7) at the manual valve. The PCM turns shift solenoid valve D ON, and shift solenoid valves A, B, and C OFF. Shift solenoid valve D pressure (SD) is applied to the left end of shift valve D, and shift valve D is moved to the right side to uncover line pressure (3) port leading to the servo valve. Line pressure (3') from shift valve D flows to the servo valve, and pushes the servo valve to the reverse position. Line pressure (1) is intercepted at cut valve B, line pressure (1B) is intercepted at shift valve B, and hydraulic pressure is not applied to the clutches.
NOTE: When used, "left" or "right" indicates direction on the hydraulic circuit.
