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 controls the shift solenoid valves ON and OFF. The shift solenoid 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 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

Port Hydraulic Pressure Port Hydraulic Pressure Port Hydraulic Pressure 
Line 5F A/T clutch pressure control solenoid valve B 55 A/T clutch pressure control solenoid valve A 
Line 5G Line, A/T clutch pressure control solenoid valve A, or B   55' A/T clutch pressure control solenoid valve A 
  3' Line 5H A/T clutch pressure control solenoid valve B 56 A/T clutch pressure control solenoid valve B 
Line 5J A/T clutch pressure control solenoid valve C 57 A/T clutch pressure control solenoid valve C 
  4' Line 5K A/T clutch pressure control solenoid valve C 90 Torque converter 
   4'' Line 5L A/T clutch pressure control solenoid valve C 91 Torque converter 
Line 5M A/T clutch pressure control solenoid valve B 92 Torque converter 
1A Line 5R A/T clutch pressure control solenoid valve C 93 ATF cooler 
1B Line 5T A/T clutch pressure control solenoid valve C 94 Torque converter 
1C Line or A/T clutch pressure control solenoid valve A SA Shift solenoid valve A 95 Lubrication 
3A Line or A/T clutch pressure control solenoid valve A SB Shift solenoid valve B 96 Torque converter 
3B Line or A/T clutch pressure control solenoid valve A SC Shift solenoid valve C 97 Torque converter 
3C Line or A/T clutch pressure control solenoid valve A SD Shift solenoid valve D 99 Suction 
5A Line or A/T clutch pressure control solenoid valve A 10 1st clutch Drain 
5B Line, A/T clutch pressure control solenoid valve A, or C 20 2nd clutch HX High position drain 
5C A/T clutch pressure control solenoid valve C 30 3rd clutch AX Air drain 
5D Line or A/T clutch pressure control solenoid valve A 40 4th clutch 
5E Line or A/T clutch pressure control solenoid valve B 50 5th clutch 

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:

  • The shift solenoid valve A is turned OFF, the shift valve A stays on the right side, and the cut A valve stays on the left side.
  • The shift solenoid valve B is turned OFF, and the shift valve B stays on the right side.
  • The shift solenoid valve C is turned OFF, and the shift valve C stays on the right side.
Line pressure (1) passes through the manual valve and stops at the cut B valve. Line pressure (1) also flows to shift solenoid valves, and the 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.
  • The illustration shows the hydraulic circuit of the 7-position transmission; the 5-position transmission circuit is much the same except for manual valve shift positions.

 

D Position: 1st gear shifting from the N position

Shift solenoid valves and shift valves remain the same as in the N position when shifting to the D position from the N position. The PCM actuates the 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 lock-up shift valve, shift valve B, manual valve, and shift valve A, and becomes 1st clutch pressure (10) at shift valve C. 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 the D position from the N position.

NOTE:

  • When used, ‘‘left'' or ‘‘right'' indicates direction on the hydraulic circuit.
  • The illustration shows the hydraulic circuit of the 7-position transmission; the 5-position transmission circuit is much the same except for manual valve shift positions.

 

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 keep OFF. Shift solenoid valve B pressure (SB) is applied to the right end of shift valve B. Shift valve B is moved to left side to uncover the line pressure port leading to the 1st clutch, and to cover the A/T clutch pressure control solenoid valve A pressure port. Line pressure (1B) passed through shift valve B flows to 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.
  • The illustration shows the hydraulic circuit of the 7-position transmission; the 5-position transmission circuit is much the same except for manual valve shift positions.

 

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 keeps ON, and C keeps OFF. Shift solenoid valve A pressure (SA) is applied to the right end of shift valve A and to the left side of the cut A valve. The cut A valve 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 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.
  • The illustration shows the hydraulic circuit of the 7-position transmission; the 5-position transmission circuit is much the same except for manual valve shift positions.

 

Hydraulic Flow (cont'd)


D Position: Driving in 2nd gear

The PCM turns shift solenoid valve B OFF, shift solenoid valve A keeps ON, and C keeps 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. The cut B valve 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.
  • The illustration shows the hydraulic circuit of the 7-position transmission; the 5-position transmission circuit is much the same except for manual valve shift positions.

 

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. Shift solenoid valve B and C keep 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 the cut A valve is released. The cut A valve is kept in the right side by line pressure (4) even though releasing shift solenoid valve A pressure (SA). Shift valve A is moved to the right side to switch line pressure (5G) port to 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 clutch 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.
  • The illustration shows the hydraulic circuit of the 7-position transmission; the 5-position transmission circuit is much the same except for manual valve shift positions.

 

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 keep OFF. Shift solenoid valve C pressure (SC) is applied to the right end of shift valve C and cut B valve. Shift valve C is moved to left side to release 2nd clutch pressure. The 3rd clutch keeps on engaging with A/T clutch pressure control solenoid valve C pressure mode.

NOTE:

  • When used, ‘‘left'' or ‘‘right'' indicates direction on the hydraulic circuit.
  • The illustration shows the hydraulic circuit of the 7-position transmission; the 5-position transmission circuit is much the same except for manual valve shift positions.

 

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 keeps OFF, and C keeps ON. Shift solenoid valve A is turned ON, and shift solenoid valve A pressure (SA) is applied to the right end of shift valve A and left end of the cut A valve. Shift valve A is moved to the left side to switch line pressure (5L) port to A/T clutch pressure control solenoid valve C pressure (5K) port leading to the 3rd clutch. Also shift valve A uncovers 4th clutch pressure (40) port leading A/T clutch pressure control solenoid valve B pressure (5H) to the 4th clutch. The 3rd clutch and 4th 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.
  • The illustration shows the hydraulic circuit of the 7-position transmission; the 5-position transmission circuit is much the same except for manual valve shift positions.

 

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 keep ON. Shift solenoid valve B pressure (SB) is applied to the right end of shift valve B and the left end of the servo control valve. Shift valve B is moved to left side to release 3rd clutch pressure. The 4th clutch keeps on engaging with A/T clutch pressure control solenoid valve B pressure mode.

NOTE:

  • When used, ‘‘left'' or ‘‘right'' indicates direction on the hydraulic circuit.
  • The illustration shows the hydraulic circuit of the 7-position transmission; the 5-position transmission circuit is much the same except for manual valve shift positions.

 

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. Shift solenoid valve B and C keep ON. Shift solenoid valve A is turned OFF, and shift solenoid valve A pressure (SA) in the right end of shift valve A is released. The cut A valve is kept in the right side by line pressure (4) even though releasing shift solenoid valve A pressure (SA). 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 clutch and 5th 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.
  • The illustration shows the hydraulic circuit of the 7-position transmission; the 5-position transmission circuit is much the same except for manual valve shift positions.

 

Hydraulic Flow (cont'd)


D Position: Driving in 5th gear

The PCM turns shift solenoid valve C OFF, shift solenoid valve A keeps OFF, and B keeps ON. Shift solenoid valve C is turned OFF, and shift solenoid valve C pressure (SC) in the right end of shift valve C is released. Shift valve C is moved to the right side to release 4th clutch pressure. The 5th clutch keeps on engaging with A/T clutch pressure control solenoid valve C pressure mode.

NOTE:

  • When used, ‘‘left'' or ‘‘right'' indicates direction on the hydraulic circuit.
  • The illustration shows the hydraulic circuit of the 7-position transmission; the 5-position transmission circuit is much the same except for manual valve shift positions.

 

2 Position

The PCM controls the shift solenoid valves and 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, and shift valve A is moved to the left side.
  • Shift solenoid valve B is turned OFF, and shift valve B is in the right side.
  • Shift solenoid valve C is turned OFF, and shift valve C is in the left side.
Line pressure (4) from the manual valve becomes 2nd clutch pressure (20) at shift valve A, via shift valves C and B. 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 and 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, and shift valve A is in the right side.
  • Shift solenoid valve B is turned ON, and shift valve B is moved to the left side.
  • Shift solenoid valve C is turned OFF, and shift valve C is in the right side.
Line pressure (1) from the manual valve flows to the cut B valve, cut A valve, 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, line pressure (1) becomes line pressure (1), (3), and (7) at the manual valve. The PCM turns shift solenoid valve C and D ON, and shift solenoid valves A and B 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. 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 lock-up shift valve, shift valve B, manual valve, servo valve, shift valve D, and cut A valve. A/T clutch pressure control solenoid valve A pressure (3C) becomes 5th clutch pressure (50) at the cut A valve. 5th clutch pressure (50) is applied to the 5th clutch, and the 5th clutch is engaged with the A/T clutch pressure control solenoid valve A pressure mode.

NOTE:

  • When used, ‘‘left'' or ‘‘right'' indicates direction on the hydraulic circuit.
  • The illustration shows the hydraulic circuit of the 7-position transmission; the 5-position transmission circuit is much the same except for manual valve shift positions.

 

Hydraulic Flow (cont'd)


R Position: Driving in reverse gear

The PCM turns shift solenoid valves B ON, and shift solenoid valve A keeps OFF and, C and D keep 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 the R position is selected while the vehicle is moving forward at speed over 10 km/h (6 mph), the PCM outputs to turn the 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.
  • The illustration shows the hydraulic circuit of the 7-position transmission; the 5-position transmission circuit is much the same except for manual valve shift positions.

 

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 the cut B valve, 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.
  • The illustration shows the hydraulic circuit of the 7-position transmission; the 5-position transmission circuit is much the same except for manual valve shift positions.