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'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. The shift valve intercepts 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, line pressure changes to shift solenoid valve pressure at the shift solenoid valve, then the solenoid valve pressure flows to the shift valve. Applying shift solenoid pressure to the shift valves 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 for engaging smoothly. The clutches are received 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 is as follows:
PORT NO. DESCRIPTION OF PRESSURE PORT NO. DESCRIPTION OF PRESSURE 
LINE SC SHIFT SOLENOID VALVE C 
LINE SE SHIFT SOLENOID VALVE E 
3' LINE 10 1ST CLUTCH 
LINE 20 2ND CLUTCH 
4' LINE 30 3RD CLUTCH 
4'' LINE 40 4TH CLUTCH 
LINE 55 A/T CLUTCH PRESSURE CONTROL SOLENOID VALVE A 
1A LINE or A/T CLUTCH PRESSURE CONTROL SOLENOID VALVE A 55' A/T CLUTCH PRESSURE CONTROL SOLENOID VALVE A 
1B LINE 56 A/T CLUTCH PRESSURE CONTROL SOLENOID VALVE B 
3A LINE 57 A/T CLUTCH PRESSURE CONTROL SOLENOID VALVE C 
3B LINE 90 TORQUE CONVERTER 
3C LINE 91 TORQUE CONVERTER 
5A LINE 92 TORQUE CONVERTER 
5B LINE 93 ATF COOLER 
5C LINE 94 TORQUE CONVERTER 
5D LINE 95 LUBRICATION 
5E LINE or A/T CLUTCH PRESSURE CONTROL SOLENOID VALVE B 96 TORQUE CONVERTER 
5F LINE or A/T CLUTCH PRESSURE CONTROL SOLENOID VALVE A or B 97 TORQUE CONVERTER 
5G A/T CLUTCH PRESSURE CONTROL SOLENOID VALVE B 99 SUCTION 
5H A/T CLUTCH PRESSURE CONTROL SOLENOID VALVE C DRAIN 
5K A/T CLUTCH PRESSURE CONTROL SOLENOID VALVE C HX HIGH POSITION DRAIN 
SA SHIFT SOLENOID VALVE A AX AIR DRAIN 
SB SHIFT SOLENOID VALVE B   

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 valves are as follows:

  • Shift solenoid valve A: OFF Shift valve A remains in right side
  • Shift solenoid valve B: ON Shift valve B moves to left side
  • Shift solenoid valve C: ON Shift valve C moves to left side
  • Shift solenoid valve E: OFF Shift valve E remains in left side
Line pressure (1) flows to the shift solenoid valves and the A/T clutch pressure control solenoid valve A, and changes to A/T clutch pressure control solenoid valve A pressure (55) at the A/T clutch pressure control solenoid valve A. A/T clutch pressure control solenoid valve A pressure (55) becomes to line pressure (1B) at the shift valve A, and stops at the manual valve. 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 [N] position

Shift solenoid valves remain the same as in [N] position, when shifting to [D] position from [N]. The manual valve is moved to [D] position, and switches the port of line pressure (4) leading to the A/T clutch pressure control solenoid valves. Hydraulic pressure line to the 1st clutch from the A/T clutch pressure control solenoid valve A is created as shift solenoid valve A is OFF, B and C remain ON. A/T clutch pressure control solenoid valve A pressure (55) changes to 1st clutch pressure (10) at the shift valve B, and flows to the 1st clutch. A/T clutch pressure control solenoid valves B and C pressures also flow to the 2nd and 3rd clutches. The 2nd and 3rd clutch engagement reduces 1st clutch engaging shock. The 1st clutch is engaged gently when shifting to [D] position 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 valves A ON, and remains B and C ON, E OFF. Shift solenoid valve A pressure (SA) is applied to the right side of the shift valve A. The shift valve A is moved to the left side to uncover the port of line pressure leading to the 1st clutch, and to cover the ports of A/T clutch pressure control solenoid valve pressures. Then A/T clutch pressure control solenoid valves pressures are released at the shift valve A.

Fluid flows to the 1st clutch by way of:
Line pressure (1) ® A/T clutch pressure control solenoid valve A-A/T clutch pressure control solenoid valve A pressure (55) ® CPB valve-Line pressure (1A) ® Shift valve A-Line pressure (1B) ® Manual valve-Line pressure ( 5A) ® Shift valve C-Line pressure (5B) ® Shift valve B-1st clutch pressure (10) ® 1st clutch
The 1st clutch pressure (10) is applied to the 1st clutch, and the 1st clutch is engaged securely.

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 prescribed value, the PCM turns shift solenoid valves A OFF, and remains B and C ON, E OFF. Shift solenoid valve A pressure (SA) in the right side of the shift valve A is released. The shift valve A is moved to the right side to uncover the ports of A/T clutch pressure control solenoid valves pressures leading to the 1st, 2nd, and 3rd clutches. The PCM controls the A/T clutch pressure control solenoid valves to regulate hydraulic pressure. A/T clutch pressure control solenoid valve B pressure (56) changes to 2nd clutch pressure (20) at the shift valve A, and flows to the 2nd clutch. The 2nd clutch is engaged gently.

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 valves C OFF and remains A and E OFF, B ON. Shift solenoid valve C pressure (SC) in the right side of the shift valve C is released. The shift valve C is moved to the right side to switch the ports. This movement covers A/T clutch pressure control solenoid valves pressures to stop at the shift valve C and B, and uncover the port of line pressure leading to the 2nd clutch.

Fluid flows to 2nd clutch by way of:
Line pressure (1) ® Manual valve-Line pressure (4) ® Shift valve C-Line pressure (5E) ® Shift valve B-Line pressure (5F) ® Shift valve A-2nd clutch pressure (20) ® 2nd clutch
The 2nd clutch pressure (20) is applied to the 2nd clutch, and the 2nd clutch is engaged securely.

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 prescribed value, the PCM turns shift solenoid valves C ON, and remains A and E OFF, B ON. Shift solenoid valve C pressure (SC) is applied to the right side of the shift valve C. The shift valve C is moved to the left side to uncover the ports of A/T clutch pressure control solenoid valves pressures leading to the 1st, 2nd, and 3rd clutches. The PCM controls the A/T clutch pressure control solenoid valves to regulate hydraulic pressure. A/T clutch pressure control solenoid valve B pressure (56) changes to 2nd clutch pressure (20) at the shift valve A, and A/T clutch pressure control solenoid valve C pressure (57) changes to 3rd clutch pressure (30) at the shift valve A. The 2nd and 3rd clutches are engaged gently.

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 valves B OFF, and remains A and E OFF, C ON. Shift solenoid valve B pressure (SB) in the right side of the shift valve B is released, and the shift valve B is moved to the right side. This movement switches the port of A/T clutch pressure control solenoid valve C pressure leading to the 3rd clutch.
A/T clutch pressure control solenoid valve C pressure (57) changes to (5K) at the shift valve B, and becomes to 3rd clutch pressure (30) at the shift valve A. The 3rd clutch pressure (30) is applied to the 3rd clutch, and the 3rd clutch is engaged securely.

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 prescribed value, the PCM turns shift solenoid valves C OFF, and remains A, B and E OFF. Shift solenoid valve C pressure (SC) in the right side of the shift valve C is released. The shift valve C is moved to the right side to uncover the ports of A/T clutch pressure control solenoid valves A and B pressures leading to the 2nd and 4th clutches. The PCM controls the A/T clutch pressure control solenoid valves to regulate hydraulic pressure. A/T clutch pressure control solenoid valve A pressure changes to 2nd clutch pressure (20) at the shift valve A, and A/T clutch pressure control solenoid valve B pressure changes to 4th clutch pressure (40) at the shift valve B. The 3rd clutch pressure is regulated to low by the A/T clutch pressure control solenoid valve C. The 3rd and 4th clutches are engaged gently.

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 valves A ON, and remains B, C and E OFF. Shift solenoid valve A pressure (SA) is applied to the right side of the shift valve A. The shift valve A is moved to the left side to cover the ports of A/T clutch pressure control solenoid valves A and C pressure leading to the 2nd and 3rd clutches.
A/T clutch pressure control solenoid valve B pressure (56) changes to (5G) at the shift solenoid valve C, and becomes to 4th clutch pressure (40) at the shift valve B. The 4th clutch pressure (40) is regulated to high by the A/T clutch pressure control solenoid valve B, and the 4th clutch is engaged securely.

NOTE: When used, ‘‘left'' or ‘‘right'' indicates direction on the hydraulic circuit.

 

[2] Position

The PCM controls the shift solenoid valves. The conditions of the shift solenoid valves and positions of the shift valves are as follows:

  • Shift solenoid valve A: OFF Shift valve A remains in right side
  • Shift solenoid valve B: ON Shift valve B moves to left side
  • Shift solenoid valve C: OFF Shift valve C remains in right side
  • Shift solenoid valve E: OFF Shift valve E remains in left side

Line pressure (1) changes (4) at the manual valve, and flows to the shift valve C. Line pressure (4) becomes the 2nd clutch pressure (20) at the shift valve A.

Fluid Flows to 2nd clutch by way of:
Line pressure (1) ® Manual valve-Line pressure (4) ® Shift valve C-Line pressure (5E) ® Shift valve B-Line pressure ( 5F) ® Shift valve A-2nd clutch pressure (20) ® 2nd clutch

The 2nd clutch pressure (20) is applied to the 2nd clutch, and the 2nd clutch is engaged.

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. The conditions of the shift solenoid valves and positions of the shift valves are as follows:

  • Shift solenoid valve A: ON Shift valve A moves to left side
  • Shift solenoid valve B: ON Shift valve B moves to left side
  • Shift solenoid valve C: ON Shift valve C moves to left side
  • Shift solenoid valve E: OFF Shift valve E remains in left side

Line pressure (1) flows to the shift solenoid valves and the A/T clutch pressure control solenoid valve A, and changes to A/T clutch pressure control solenoid pressure (55) at the A/T clutch pressure control solenoid valve A.

Fluid Flows to 1st clutch by way of:
A/T clutch pressure control solenoid pressure (55) ® CPB valve-Line pressure (1A) ® Shift valve A-Line pressure (1B) ® Manual valve-Line pressure (5A) ® Shift valve C-Line pressure (5B) ® Shift valve B-1st clutch pressure (10) ® 1st clutch

The 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 [R] position from [P] or [N] position

When shifting in [R] position, the PCM turns shift solenoid valves B and E ON, A and C OFF. Shift solenoid valve B pressure (SB) is applied to the right side of the shift valve B, and the shift valve B is moved to left side. Shift solenoid valve E pressure (SE) is applied to the left side of the shift valve E, and the shift valve E is moved to the right side. Line pressure (1) changes to (3) at the manual valve, and flows to the servo valve via the shift valve E. The servo valve is moved to reverse range position. Movement of the shift valves B and E, and servo valve creates 4th clutch pressure line between the 4th clutch and the A/T clutch pressure control solenoid valve A. The 4th clutch pressure (40) is applied to the 4th clutch, and the 4th clutch is engaged gently.

NOTE: When used, ‘‘left'' or ‘‘right'' indicates direction on the hydraulic circuit.

 

Hydraulic Flow (cont'd)


[R] Position: Driving in reverse gear

After starting off in reverse gear, the PCM turns shift solenoid valves A ON, and remains B and E ON, C OFF. Shift solenoid valve A pressure (SA) is applied to the right side of the shift valve A to cover the port of A/T clutch pressure control solenoid valve A pressure, and to uncover the port of line pressure leading to the 4th clutch creating full line pressure. The 4th clutch is engaged securely with line pressure.

Reverse Inhibitor Control

While the vehicle is moving forward, the PCM controls shift solenoid valve E remaining OFF. The shift valve E covers the port of line pressure (3') leading to the servo valve reverse position. The servo valve cannot be shifted to reverse position, and hydraulic pressure is not applied to the 4th clutch from servo valve for reverse, 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

Shift solenoid valves B and E are turned ON, and A, and C OFF by the PCM. Line pressure (1) flows to the shift solenoid valves and the A/T clutch pressure control solenoid valve A. Line pressure (3) changes to (3') at the shift valve E, and flows to the servo valve. The servo valve is moved to reverse/park position. Hydraulic pressure is not applied to the clutches.