Automatic Transmission/Transaxle
Hydraulic Flow
N Position
As the engine turns, the ATF pump starts to operate. Automatic transmission fluid (ATF) is drawn from (99) and discharged into (1). Then, ATF flowing from the ATF pump becomes line pressure (1). Line pressure (1) is regulated by the regulator valve. Torque converter inlet pressure (92) enters (94) of the torque converter through the lock-up shift valve and discharges into (90). The torque converter check valve prevents torque converter pressure from rising. Under this condition, hydraulic pressure is not applied to the clutches.
NOTE: When used, "left" or "right" indicates direction on the hydraulic circuit.
1 Position
Line pressure (1) flows to the manual valve and the modulator valve. Line pressure (1) changes to line pressure (4) and 1st-hold clutch pressure at the manual valve, and changes to modulator pressure at the modulator valve. Modulator pressure (6) flows to the left ends of the 1-2 shift valve and 3-4 shift valve because shift control solenoid valve A is turned OFF by the PCM. The 1-2 shift valve and the 3-4 shift valve are moved to the right side. Line pressure (4) becomes 1st clutch pressure (10) at the 1-2 shift valve. 1st clutch pressure (10) is applied to the 1st clutch, and the 1st clutch is engaged. 1sthold clutch pressure (18) flows to the 1st-hold clutch via the 3-4 shift valve and the 1-2 shift valve. Power is transmitted only during deceleration through the 1st-hold clutch.
NOTE: When used, "left" or "right" indicates direction on the hydraulic circuit.
2 Position
Line pressure (1) flows to the manual valve and the modulator valve. Line pressure (1) changes to line pressure (4) at the manual valve, and changes to modulator pressure at the modulator valve. But modulator pressure (6) does not flow to each shift valve because shift control solenoid valves A and B are turned ON by the PCM. Line pressure (4) passes through the CPB valve and the CPC valve, and changes to line pressure (5), then flows to the 1-2 shift valve. Line pressure (5) from the 1-2 shift valve changes to 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) passes through the 1-2 shift valve and the orifice, and changes to 1st clutch pressure. The 1st clutch pressure (10) also flows to the 1st clutch. However, no power is transmitted because of the one-way clutch.
NOTE: When used, "left" or "right" indicates direction on the hydraulic circuit.
D4 or D1 Position
1. 1st Gear
Fluid flow through the torque converter circuit is the same as in N position. Line pressure flows to the manual valve and the modulator valve. Line pressure changes to modulator pressure (6) at the modulator valve and to line pressure (4) at the manual valve. Modulator pressure (6) flows to the left end of the 1-2 shift valve and the 3-4 shift valve because shift control solenoid valve A is turned OFF and B is turned ON by the PCM. The 1-2 shift valve is moved to the right side. Line pressure (4) changes to 1st clutch pressure (10) at the 1-2 shift valve and the orifice. The 1st clutch pressure (10) is applied to the 1st clutch and the 1st accumulator; the vehicle will move as the engine power is transmitted.
NOTE: When used, "left" or "right" indicates direction on the hydraulic circuit.
2. 2nd Gear
As the speed of the vehicle reaches the prescribed value, shift control solenoid valve A is turned ON by the PCM. Modulator pressure (6A) in the left end of the 1-2 shift valve is released by turning shift control solenoid valve A ON. The 1-2 shift valve is moved to the left side and uncovers the port to allow line pressure (5) to the 2-3 shift valve. Line pressure (5) changes to 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.
Fluid flows by way of:
- Line Pressure (4) --> CPB Valve --> Line Pressure (5) --> 1-2 Shift Valve --> Line Pressure (5) --> 2-3 Shift Valve
- 2nd Clutch Pressure (20) --> 2nd Clutch
The hydraulic pressure also flows to the 1st clutch. However, no power is transmitted because of the one-way clutch.
NOTE: When used, "left" or "right" indicates direction on the hydraulic circuit.
3. 3rd Gear
As the speed of the vehicle reaches the prescribed value, shift control solenoid valve B is turned OFF by the PCM. Shift control solenoid valve A remains ON. Modulator pressure (6) flows to the right end of the 1-2 shift valve and the left end of the 2-3 shift valve. The 2-3 shift valve is moved to the right side by modulator pressure (61B). The 2-3 shift valve covers the port to stop line pressure (5) to the 2nd clutch, and uncovers the 3-4 shift valve as the 2-3 shift valve is moved to the right side. Line pressure (5) becomes 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.
Fluid flows by way of:
- Line pressure (4) - CPB Valve - Line Pressure (5) - 1-2 Shift Valve - Line Pressure (5) - 2-3 Shift Valve
- Line Pressure (5) - 3-4 Shift Valve - 3rd Clutch Pressure (30) - 3rd Clutch
The hydraulic pressure also flows to the 1st clutch. However, no power is transmitted because of the one-way clutch.
NOTE: When used, "left" or "right" indicates direction on the hydraulic circuit.
4. 4th Gear (D4 Position)
As the speed of the vehicle reaches the prescribed value, shift control solenoid valve A is turned OFF by the PCM. Shift control solenoid valve B remains OFF. Modulator pressure (6) flows to the left end of the 1-2 shift valve and the left end of the 3-4 shift valve. Modulator pressure (6A) in the left end of the 1-2 shift valve equals modulator pressure (6B) in the right end of the 1-2 shift valve. The 1-2 shift valve remains at left side by the tension of the valve spring.
The 3-4 shift valve is moved to the right side by modulator pressure (6A). The 3-4 shift valve covers the port to the 3rd clutch and uncovers the port to the 4th clutch as this valve is moved to the right side. The 4th clutch pressure (41) from the 3-4 shift valve becomes 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.
Fluid flows by way of:
- Line pressure (4) --> CPB Valve --> Line Pressure (5) --> 1-2 Shift Valve --> Line Pressure (5) --> 2-3 Shift Valve
- Line Pressure (5) --> 3-4 Shift Valve --> 4th Clutch Pressure (41) --> Manual Valve --> 4th Clutch Pressure (40)
-->4th Clutch
The hydraulic pressure also flows to the 1st clutch. However, no power is transmitted because of the one-way clutch.
NOTE: When used, "left" or "right" indicates direction on the hydraulic circuit.
R Position
Fluid flow through the torque converter circuit is the same as in N position. Line pressure (1) changes to line pressure (3) and flows to the 1-2 shift valve. Line pressure (3) changes to line pressure (3') at the 1-2 shift valve and flows to the servo valve. The servo valve is moved to the right side (Reverse range position) and uncovers the port to allow line pressure (3") to the manual valve. Line pressure (3') from the 1-2 shift valve flows through the servo valve to the manual valve and changes to 4th clutch pressure (40). 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 control solenoid valves A and B; shift control solenoid valve A is turned OFF, shift control 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 4th clutch pressure (40) is not applied to the 4th clutch, 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
Fluid flow through the torque converter circuit is the same as in N position. Line pressure (1) changes to line pressure (3) and flows to the 1-2 shift valve. Line pressure (3) changes to line pressure (3') at the 1-2 shift valve and flows to the servo valve. The servo valve is moved to the right side (Reverse range position) and uncovers the port to allow line pressure (3") to the manual valve as in R position. Line pressure (3") from the servo valve is intercepted by the manual valve. Hydraulic pressure is not supplied to the clutches, and power is not transmitted,
NOTE: When used, "left" or "right" indicates direction on the hydraulic circuit.