Automatic Transmission/Transaxle
Hydraulic FlowDistribution 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's 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 controls the shift solenoid valves ON and OFF, and 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 A/T clutch pressure control solenoid valves A and B.
The A/T clutch pressure control solenoid valves regulated the A/T clutch pressure control solenoid pressure and apply the A/T clutch pressure control 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 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.
Engaging the clutch with line pressure happens when shifting is completed.
Hydraulic pressure at the parts is as follows:
NOTE:
- CPC: Clutch Pressure Control pressure
- SH: Shift Solenoid pressure
- LS: A/T Clutch Pressure Control Solenoid pressure
- LC: Torque Converter Clutch Solenoid pressure
N Position
The PCM controls the shift solenoid valves. The conditions of the shift solenoid valve and positions of the shift valve are as follows:
- The shift solenoid valve A is turned OFF, and the shift valve A is moved to the left side.
- The shift solenoid valve B is turned ON, and the shift valve B remains in the right side.
- The shift solenoid valve C is turned OFF, and the shift valve C remains in the left side.
Line pressure (1) passes through the manual valve and stops at shift valve D. Line pressure (1) also flows to the modulator valve, and becomes modulator pressure (6). Modulator pressure (6) flows to the shift solenoid valves and the A/T clutch pressure control solenoid valves. Under this condition, hydraulic pressure is not applied to the clutches.
NOTE:
- When used, "left" or "right" indicates direction on the hydraulic circuit.
- Hydraulic circuit shows the '98-99 models; the '00-02 models are similar.
D4 Position; 1st gear shifting from N position
The PCM turns the shift solenoid valves A and C ON when shifting to D4 position from N. Shift solenoid valve B remains ON. Shift solenoid valve C is turned ON, and SH C pressure (SC) in the right side of the shift valve C is released, then the shift valve C is moved to the right side. Shift solenoid valve A is turned ON, and SH A pressure (SA) in the left side of the shift valve A is released, then shift valve A is moved to the right side. The A/T clutch pressure control solenoid valve A regulates LS A pressure (56) and applies it to CPC valve A. Line pressure (1) becomes line pressure (4) at the manual valve, and flows to shift valve C and CPC valve A. Line pressure (4) becomes CPC A pressure (4A) and passes through shift valve C, A, and B. then CPC A pressure (4A) becomes 1st clutch pressure (10) at shift valve 1st clutch pressure (10) is applied to the 1st clutch, then the 1st clutch is engaged with pressure of the CPC pressure mode. Line pressure (4) passes through shift valve A and B. then stops at shift valve B.
NOTE:
- When used, "left" or "right" indicates direction on the hydraulic circuit.
- Hydraulic circuit shows the '98-99 models; the '00-02 models are similar.
D4 Position: Driving in 1st gear
The PCM turns shift solenoid valve A OFF, but shift solenoid valves B and C remain ON. SH A pressure (SA) is applied to the left side of shift valve A, then shift valve A is moved to the left side. This movement switches the port of line pressure and CPC pressure on shift valve A. The 1st clutch pressure is changed to line pressure mode, and the 1st clutch is engaged securely. CPC A pressure (5E) stops at shift valve B.
NOTE:
- When used, "left" or "right" indicates direction on the hydraulic circuit.
- Hydraulic circuit shows the '98-99 models; the '00-02 models are similar.
D4 Position: Shifting between 1st gear and 2nd gear
As the speed of the vehicle reaches the prescribed value, the PCM turns shift solenoid valve A OFF. Shift solenoid valves B and C remain ON. Then shift solenoid valve A is turned ON, and SH A pressure (SA) in the left side of the shift valve A is released. Shift valve A is moved to the right side to switch the port of line pressure and CPC pressure. The PCM also controls the A/T clutch pressure control solenoid valves. The A/T clutch pressure control solenoid valves A and B apply their pressure to the CPC valves A and B. Line pressure (4) becomes CPC B pressure (4B) at the CPC valve B. and CPC B pressure passes through shift valves C, B, and A, to become 2nd clutch pressure. The 1st and 2nd clutches are engaged with the CPC pressure mode.
NOTE:
- When used, "left" or "right" indicates direction on the hydraulic circuit.
- Hydraulic circuit shows the '98-99 models; the '00-02 models are similar.
D4 Position: Driving in 2nd gear
The PCM turns shift solenoid valve C OFF, and controls A/T clutch pressure control solenoid valve A to release LS A pressure (56). Shift solenoid valves A and B remain ON. Releasing LS A pressure in the CPC valve A releases CPC A pressure in the 1st clutch pressure circuit. Shift solenoid valve C is turned OFF, and SH C pressure (SC) is applied to the right side of shift valve C. Then shift valve C is moved to the left side to switch the port of line pressure and CPC pressure. The 2nd clutch pressure is changed to line pressure mode, and the 2nd clutch is engaged securely. The CPC B pressure (5D) stops at shift valve B.
NOTE:
- When used, "left" or "right" indicates direction on the hydraulic circuit.
- Hydraulic circuit shows the '98-99 models; the '00-02 models are similar.
D4 Position: Shifting between 2nd gear and 3rd gear
As the speed of the vehicle reaches the prescribed value, the PCM turns shift solenoid valve B OFF. The PCM also control A/T clutch pressure control solenoid valve A to apply LS A pressure (56) to CPC valve A. Shift solenoid valve A remains ON, and C remains OFF. Shift solenoid valve B is turned OFF, and SH B pressure (SB) is applied to the right side of shift valve B. Then shift valve B is moved to the left side to switch the port of line pressure and CPC pressure. Line pressure (4) becomes CPC A pressure (4A) at the CPC valve A. The CPC A pressure (4A) becomes 3rd clutch pressure (30) at shift valve B. and flows to the 3rd clutch. The 2nd clutch pressure is changed to CPC pressure mode by switching the position of shift valve B.
NOTE:
- When used, "left" or "right" indicates direction on the hydraulic circuit.
- Hydraulic circuit shows the '98-99 models; the '00-02 models are similar.
D4 Position: Driving in 3rd gear
The PCM turns the shift solenoid valve C ON, and controls A/T clutch pressure control solenoid valve B to release LS B pressure (57). Shift solenoid valve A remains ON, and B remains OFF. Releasing LS B pressure in the CPC valve B releases CPC B pressure in the 2nd clutch pressure circuit. Shift solenoid valve C is turned ON, and SH C pressure (SC) in the right side of shift valve C is released. Then shift valve C is moved to the right side to switch the port of line pressure and CPC pressure. The 3rd clutch pressure is changed to line pressure mode, and the 3rd clutch is engaged securely. The CPC A pressure (4A) stops at shift valve E.
NOTE:
- When used, "left" or "right" indicates direction on the hydraulic circuit.
- Hydraulic circuit shows the '98-99 models; the '00-02 models are similar.
D4 Position: Shifting between 3rd gear and 4th gear
As the speed of the vehicle reaches the prescribed value, the PCM turns shift solenoid valve A OFF. The PCM also controls A/T clutch pressure control solenoid valve B to apply LS B pressure (57) to CPC valve B. Shift solenoid valve B remains OFF, and C remains ON. Shift solenoid valve A is turned OFF, and SH A pressure (SA) is applied to the left side of shift valve A. Then shift valve A is moved to the left side to switch line pressure and CPC pressure. Line pressure (4) becomes CPC B pressure (4B) at CPC valve B. The CPC B pressure (4B) becomes 4th clutch pressure (41) at shift valve D, and flows to the 4th clutch via the manual valve. The 3rd clutch pressure is changed to CPC pressure mode by switching the position of shift valve A.
NOTE:
- When used, "left" or "right" indicates direction on the hydraulic circuit.
- Hydraulic circuit shows the '98-99 models; the '00-02 models are similar.
D4 Position: Driving in 4th gear
The PCM turns shift solenoid valve C OFF, and controls A/T clutch pressure control solenoid valve A to release LS A pressure (56). Shift solenoid valves A and B remain OFF. Releasing LS A pressure (56) releases CPC A pressure in the 3rd clutch pressure circuit. Shift solenoid valve C is turned OFF, and SH C pressure (SC) is applied to the right side of shift valve C. Then shift valve C is moved to the left side to switch the port of line pressure and CPC pressure. The CPC B pressure (5B) changes to line pressure (5B) at shift valve C, and flows to the 4th clutch via shift valve B. shift valve C, shift valve D, and the manual valve. The 4th clutch pressure is changed to line pressure mode by switching the position of shift valve C, and 4th clutch is engaged securely. The CPC B pressure (5D) stops at shift valve A.
NOTE:
- When used, "left" or "right" indicates direction on the hydraulic circuit.
- Hydraulic circuit shows the '98-99 models; the '00-02 models are similar.
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 positions of the shift valve are as follows:
- Shift solenoid valve A is turned ON, and the shift valve A is in the right side.
- Shift solenoid valve B is turned ON, and the shift valve B is in the right side.
- Shift solenoid valve C is turned OFF, and the shift valve C is moved to the left side. The PCM also controls A/T clutch pressure control solenoid valve B to apply LS B pressure (57) to CPC valve B.
Line pressure (4) from the manual valve becomes line pressure (5C) at shift valve C. Line pressure (5C) flows to shift valve A via shift valve B. and becomes 2nd clutch pressure (20). The 2nd clutch pressure is applied to the 2nd clutch, and 2nd clutch is engaged.
NOTE:
- When used, "left" or "right" indicates direction on the hydraulic circuit.
- Hydraulic circuit shows the '98-99 models; the '00-02 models are similar.
1 Position
The PCM the shift solenoid valves and the A/T clutch pressure control solenoid valves. The conditions of the shift solenoid valves and the positions of the shift valve are as follows:
- Shift solenoid valve A is turned OFF, and shift valve A is moved to the left side.
- Shift solenoid valve B is turned ON, and shift valve B is in the right side.
- Shift solenoid valve C is turned ON, and shift valve C is in the right side.
Line pressure (4) becomes line pressure (5B) at shift valve C. Line pressure (5C) flows to shift valve B via shift valve A, and becomes 1st clutch pressure (10). 1st clutch pressure (10) is applied to the 1st clutch, then 1st clutch is engaged.
NOTE:
- When used, "left" or "right" indicates direction on the hydraulic circuit.
- Hydraulic circuit shows the '98-99 models; the '00-02 models are similar.
R Position: Shifting to R position from P or N position
Line pressure (1) becomes line pressure (3) at the manual valve, and flows to the reverse CPC valve. Line pressure (3) is regulated by the reverse CPC valve and becomes line pressure (3'). Line pressure (3') pushes the servo valve to the reverse position, passes through the servo valve, and flows to the manual valve. Line pressure (3') becomes 4th clutch pressure (40). The 4th clutch pressure (40) is applied to the 4th clutch, and 4th clutch is engaged with the reverse CPC pressure mode.
NOTE:
- When used, "left" or "right" indicates direction on the hydraulic circuit.
- Hydraulic circuit shows the '98-99 models; the '00-02 models are similar.
R Position: Driving in reverse gear
The PCM turns shift solenoid valve C OFF. Shift solenoid valve A remains OFF, and B remains ON. Shift solenoid valve C is turned OFF, and SH C pressure (SC) is applied to the right side of the reverse CPC valve. Then the reverse CPC valve moves to the left side, creating full line pressure. Line pressure to the 4th clutch is same as shifting to R position, and 4th clutch pressure increases. The 4th clutch is engaged with line pressure mode.
NOTE:
- When used, "left" or "right" indicates direction on the hydraulic circuit.
- Hydraulic circuit shows the '98-99 models; the '00-02 models are similar.
P Position
Shift solenoid 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.
NOTE:
- When used, "left" or "right" indicates direction on the hydraulic circuit.
- Hydraulic circuit shows the '98-99 models; the '00-02 models are similar.