Hydraulic Flow
Hydraulic FlowAs the engine turns, the ATF pump starts to operate. Automatic transmission fluid (ATF) is drawn through the ATF strainer 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 A and B ON and OFF, and shift solenoid valves A and B apply modulator pressure to the shift valves. Applying modulator pressure to the shift valves moves the position of the shift valve, and switches the port of hydraulic pressure. The PCM also controls the A/T clutch pressure control solenoid valves A and B. The A/T clutch pressure control solenoid valve A regulates linear solenoid pressure and applies linear solenoid pressure to the CPC valves. The CPC valve regulates CPC pressure and controls to shift smoothly between upper and lower gears.
Hydraulic pressure at the port is as follows:
N Position
The PCM turns the shift solenoid valve A and B OFF. Line pressure (1) passes through the manual valve, but it does not flow to the clutches. Line pressure (1) also flows to the modulator valve and becomes to modulator pressure (6).
Modulator pressure (6) flows to the shift valves by means of the shift solenoid valves A and B OFF.
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 D17A1 engine model; the D17A2 engine does not have the 3rd sub accumulator.
D or D3 Position in 1st gear
When shifting into the D or D3 position from N, the manual valve uncovers the port leading line pressure (4) to the 1st clutch, and the PCM turns the shift solenoid valve B ON, but shift solenoid valve A remains OFF. Modulator (SH B) pressure (6B) in the right side of the 1-2 shift valve and in the left side of the 2-3 shift valve is released, then 1-2 shift valve is moved to the right side and 2-3 shift valve is moved to the left side. The 1-2 shift valve creates 1st clutch circuit bypass to reduce engaging shock of the 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.
^ The illustration shows the D17A1 engine model; the D17A2 engine does not have the 3rd sub accumulator.
D or D3 Position in 2nd gear
As the speed of the vehicle reaches the prescribed value, the PCM turns the shift solenoid valve A ON. Shift solenoid valve B remains ON, and modulator (SH A) pressure (6A) in the left side of the 1-2 shift valve and 3-4 shift valve is released. The 1-2 and 3-4 shift valves are moved to the left side, and the 1-2 shift valve uncovers the port leading CPC pressure (5) to the 2-3 shift valve. CPC pressure (5) becomes 2nd clutch pressure (20) at the 2-3 shift valve. The 2nd clutch pressure (20) is applied to the 2nd clutch, and the 2nd clutch is engaged.
Line pressure (4) also flows to the 1st clutch, and the 1st clutch is engaged. However, no power is transmitted because of the one-way clutch.
NOTE:
^ When used, "left" or "right" indicates direction on the hydraulic circuit.
^ The illustration shows the D17A1 engine model; the D17A2 engine does not have the 3rd sub accumulator.
D or D3 Position in 3rd gear
As the speed of the vehicle reaches the prescribed value, the PCM turns the shift solenoid valve B OFF. Shift solenoid valve A remains ON, and modulator (SH B) pressure (6B) is applied to the right side of the 1-2 shift valve and to the left side of the 2-3 shift valve. The 2-3 shift valve is moved to the right side to switch the port leading CPC pressure (5) to the 3-4 shift valve, then CPC pressure (51 becomes the 3rd clutch pressure (30) at the 3-4 shift valve. The 3rd clutch pressure (30) is applied to the 3rd clutch, and the 3rd clutch is engaged.
Line pressure (4) also flows to the 1st clutch, and the 1st clutch is engaged. However, no power is transmitted because of the one-way clutch.
NOTE:
^ When used, "left" or "right" indicates direction on the hydraulic circuit.
^ The illustration shows the D17A1 engine model; the D17A2 engine does not have the 3rd sub accumulator.
D Position in 4th gear
As the speed of the vehicle reaches the prescribed value, the PCM turns the shift solenoid valve A OFF. Shift solenoid valve B remains OFF, and modulator (SH A) pressure (6A) is applied to the left side of the 3-4 shift valve.
The 3-4 shift valve is moved to the right side to switch the port CPC pressure (5) to the 4th clutch pressure (41), the 4th clutch pressure (41) becomes the 4th clutch pressure (40) at the manual valve. The 4th clutch pressure (40) is applied to the 4th clutch, and the 4th clutch is engaged.
Line pressure (4) also flows to the 1st clutch, and the 1st clutch is engaged. However, no power is transmitted because of the one-way clutch.
NOTE:
^ When used, "left" or "right" indicates direction on the hydraulic circuit.
^ The illustration shows the D17A1 engine model; the D17A2 engine does not have the 3rd sub accumulator.
2 Position
The PCM turns the shift solenoid valves A and B ON. The 1-2 shift valve and 2-3 shift valve uncover the ports leading CPC pressure (5) to the 2nd clutch, CPC pressure (5) becomes the 2nd clutch pressure (20) at the 2-3 shift valve. The 2nd clutch pressure (20) is applied to the 2nd clutch, and the 2nd clutch is engaged.
Line pressure (4) passed through the manual valve also flows to the 1st clutch, and the 1st clutch is engaged. However, no power is transmitted because of the one-way clutch.
NOTE:
^ When used, "left" or "right" indicates direction on the hydraulic circuit.
^ The illustration shows the D17A1 engine model; the D17A2 engine does not have the 3rd sub accumulator.
R Position
The PCM turns the shift solenoid valves A ON and B OFF, and modulator (SH B) pressure (6B) is applied to the right side of the 1-2 shift valve and to the left side of the 2-3 shift valve. Line pressure (3) passed through the manual valve flows to the 1-2 shift valve, and changed to line pressure (3'). Line pressure (3') pushes the servo valve to the reverse/park position, passes through the servo valve, and flows to the manual valve. Line pressure (3') becomes the 4th clutch pressure (40) at the manual valve. The 4th clutch pressure (40) is applied to the 4th clutch, and the 4th clutch is engaged.
Reverse Inhibitor Control
When the R position is selected while the vehicle is moving forward at speeds over 6 mph (10 km/h), the PCM outputs the 1st speed signal to shift solenoid valves A and B; shift solenoid valve A is OFF, and shift solenoid valve B is turned ON. The 1-2 shift valve is moved to the right side and covers the port to stop line pressure (3') to the servo valve. Line pressure (3') is not applied to the servo valve, and the 4th clutch pressure (40) is not applied to the 4th clutch. Power is not transmitted to the reverse direction.
NOTE:
^ When used, "left" or "right" indicates direction on the hydraulic circuit.
^ The illustration shows the D17A1 engine model; the D17A2 engine does not have the 3rd sub accumulator.
P Position
Line pressure (3) passed through the manual valve flows to the 1-2 shift valve, and changed to line pressure (3'). Line pressure (3') pushes the servo valve to the reverse/park position, passes through the servo valve, and flows to the manual valve. Line pressure (3') is intercepted at the manual valve, 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 D17A1 engine model; the D17A2 engine does not have the 3rd sub accumulator.