1995 ACURA TL Service Repair Manual

Hydraulic Flow

General Chart of Hydraulic Pressure

ATF Pump

Line Pressure
Modulator Pressure

Throttle B Pressure

Clutch Pressure

Torque Converter Pressure

Lubrication Pressure

Distribution of Hydraulic Pressure

Regulator Valve
Torque Converter Pressure

Lubrication Pressure

To Regulate Line Pressure

Manual Valve

Modulator Valve
To Select Line Pressure

Modulator Pressure

1-2 Shift Valve

2-3 Shift Valve

3-4 Shift Valve

Throttle Valve
Clutch Pressure

Throttle B Pressure
Clutch Pressure

Shift Control Solenoid Valves

Lock-up Control Solenoid Valves
Regulator ValveProCarManuals.com

Description

Position

As the engine turns, the ATF pump also starts to operate. Automatic transmission fluid (ATF) is drawn from (99) and dis-

charged into (1). Then, ATF flowing from the ATF pump becomes the line pressure (1). The line pressure (1) is regulated

by the regulator valve. The 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 the torque converter pressure from rising.

Under this condition, the hydraulic pressure is not applied to the clutches as the manual valve stops line pressure (1).

NOTE: When used, "left" or "right" indicates direction on the hydraulic circuit.
Hydraulic Flow (cont'd)ProCarManuals.com

Position

The line pressure (1) flows to the manual valve, the modulator valve and the throttle valve. The line pressure (1) becomes

to the modulator pressure (6) at the modulator valve, and remains line pressure (4), (18) and (25) at the manual valve.

The modulator pressure (6) flows to the right end of the 1-2 and 2-3 shift valves because shift control solenoid valve A is

turned ON and B is turned OFF by the TCM, and those valves are moved to the left side. The line pressure (18) flows to the

right end of the 3-4 shift valve, and the 3-4 shift valve is moved to the left side.

The line pressure (4) becomes the 1st clutch pressure (10). The 1st clutch pressure (10) is applied to the 1st clutch, and the

1st clutch is engaged.

The line pressure (4) also becomes the 1st-hold clutch pressure (15) and it flows to the 1st-hold clutch and the 1st-hold

accumulator.

Fluid flows by way of:

- Line Pressure (4) 1-2 Shift Valve - Line Pressure (5) 2-3 Shift Valve-3rd Clutch Pressure (32) 3-4 Shift Valve -

4th Clutch Pressure (42) Orifice - 4th Clutch Pressure (41) Manual Valve - 1st-hold Clutch Pressure (16) Orifice -

1st-hold Clutch Pressure (15) 1st-hold Clutch.

Power is transmitted only during deceleration through the 1st-hold clutch.

NOTE: When used, "left" or "right" indicates direction on the hydraulic circuit.ProCarManuals.com

Description

Position

The line pressure (1) flows to the manual valve, the modulator valve and the throttle valve. The line pressure (1) becomes

modulator pressure (6) at the modulator valve, and remains line pressure (4) and (25) at the manual valve.

The modulator pressure (6) does not flow to each shift valves because shift control solenoid valves A and B are turned ON

by the
TCM.

The line pressure (4) becomes the line pressure (5) at the 1-2 shift valve, and the line pressure (5) becomes the 2nd clutch

pressure (21) at the 2-3 shift valve. The 2nd clutch pressure (21) changes the 2nd clutch pressure (20) at the orifice. The

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

The line pressure (4) also becomes the 1st clutch pressure (10). The 1st clutch pressure (10) is applied 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.
Hydraulic Flow (cont'd)ProCarManuals.com

Position

1. 1st Gear

The flow of fluid through the torque converter circuit is the same as in position.

The line pressure (1) flows to the manual valve, the modulator valve and the throttle valve. The line pressure (1)

becomes modulator pressure (6) at the modulator valve, and remains line pressure (4) at the manual valve.

The modulator pressure (6) flows to the left end of the 1-2 shift valve and right end of the 3-4 shift valve because shift

control solenoid valve A is turned OFF and B is turned ON by the TCM. The 1-2 shift valve is moved to the right side,

and the 3-4 shift valve is moved to the left side.

The line pressure (4) becomes the 1st clutch pressure (10). The 1st clutch pressure (10) is applied to the 1st clutch and

1st accumulator; consequently, the vehicle will move as the engine power is transmitted.

In or position at 1st gear, the 1st-hold clutch pressure is not applied to the 1st-hold clutch because the manual

valve covers the port to leading to the 1st-hold clutch.

NOTE: When used, "left" or "right" indicates direction on the hydraulic circuit.ProCarManuals.com

Description

Position

2. 2nd Gear

As the speed of the vehicle reaches the prescribed value, shift control solenoid valve A is turned ON by means of the

TCM. Shift control solenoid valve B remains ON. The 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. The line pressure (5) becomes the 2nd clutch pressure (21) 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) 1-2 Shift Valve - Line Pressure (5) 2-3 Shift Valve - 2nd Clutch Pressure (21) Orifice - 2nd

Clutch Pressure (20) 2nd Clutch

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.

14-34
Hydraulic Flow (cont'd)ProCarManuals.com

3. 3rd Gear

As the speed of the vehicle reaches the prescribed value, shift control solenoid valve B is turned OFF by means of the

TCM. Shift control solenoid valve A remains ON. The modulator pressure (6B) flows to the right ends of the 1-2 shift

valve and the 2-3 shift valve. The 2-3 shift valve is moved to the left side by the modulator pressure (6B). The 2-3 shift

valve covers the port to stop line pressure (5) to the 2nd clutch and uncovers to the 3-4 shift valve as this valve is

moved to the left side. The line pressure (5) becomes the 3rd clutch pressure. 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) 1-2 Shift Valve - Line Pressure (5) 2-3 Shift Valve-3rd Clutch Pressure (32) 3-4 Shift Valve

- 3rd Clutch Pressure (31) Orifice - 3rd Clutch Pressure (30) 3rd Clutch

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.ProCarManuals.com

Description

Position

4. 4th Gear

As the speed of the vehicle reaches the prescribed value, shift control solenoid valve A is turned OFF by means of the

TCM. Shift control solenoid valve B remains OFF. The modulator pressure (6A) flows to the right end of the 3-4 shift

valve and the left end of the 1-2 shift valve. The modulator pressure (6A) in the left end of the 1-2 shift valve equals the

modulator pressure (6B) in the right end of the 1-2 shift valve, so 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 left side by modulator pressure (6B). The 3-4 shift valve covers the port leading to

the 3rd clutch and uncovers to the 4th clutch as this valve is moved to the left side. The 3rd clutch pressure (32) from

the 2-3 shift valve becomes the 4th clutch pressure. 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) 1-2 Shift Valve - Line Pressure (5) 2-3 Shift Valve-3rd Clutch Pressure (32) 3-4 Shift Valve

- 4th Clutch Pressure (42) Orifice - 4th Clutch Pressure (41) Manual Valve - 4th Clutch Pressure (40) 4th

clutch

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.
Hydraulic Flow (cont'd)ProCarManuals.com