1997 ACURA NSX Service Repair Manual

Hydraulic Flow
Description

General Chart of Hydraulic Pressure

Distribution of Hydraulic PressureProCarManuals.com

position

As the engine turns, the ATF pump also starts to operate. The ATF is drawn from (99) and discharged 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 torque converter through the orifice 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.ProCarManuals.com

Position

Line pressure (1) becomes line pressure (4), (18), and (25) as it passes through the manual valve. Also, line pressure (1)

goes to the modulator valve through the filter and becomes modulator pressure (6). Modulator pressure (6) is supplied to

the 1-2 shift valve and 2-3 shift valve.

The 1-2 shift and 2-3 shift valves are moved to the left side because the shift control solenoid valve A is turned ON and B

is OFF by the
TCM.

The line pressure (18) is supplied to the 3-4 shift valve, and moves the valve to the left side. Line pressure (4) becomes 1st

clutch pressure (10), and the 1st clutch is engaged.

Line pressure (4) becomes 1st-hold clutch pressure (16) via the 1-2 shift valve, 2-3 shift valve, 3-4 shift valve, and manual

valve, and the 1st-hold clutch is engaged.

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

Position

Line pressure (1) becomes the line pressure (4), (25) as it passes through the manual valve.

Line pressure (1) goes to the modulator valve and becomes the modulator pressure (6). The modulator pressure (6) is sup-

plied to the 1-2 shift valve and 3-4 shift valve. The 1-2 shift and 3-4 shift valves are moved to the left side, and the 2-3 shift

valve is moved to the right side, because the shift control solenoid valve A and B are turned OFF by the TCM.

Line pressure (4) goes through the 2nd clutch pressure (20) to the 2nd clutch, then the 2nd clutch is engaged.

Line pressure (4) passing through the orifice becomes the 1st clutch pressure (10) and flows to the 1st clutch. However no

power is transmitted by means of the one-way clutch.

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

Positions

1. 1st Gear

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

Line pressure (1) becomes line pressure (4) and 1st clutch pressure (10).

The 1st clutch pressure is applied to the 1st clutch and 1st accumulator, and the vehicle will move as engine power is

transmitted.

Line pressure (1) becomes modulator pressure (6) by the modulator valve and travels to each shift valve.

The 1-2 shift valve is moved to the right side because the shift control solenoid valve A is turned OFF and B is turned

ON by the
TCM.

Line pressure (1) also flows to the throttle valve.

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

2. 2nd Gear

The flow of fluid to the 1-2 and 2-3 shift valves is the same as in 1st gear. As the speed of the vehicle reaches the pre-

scribed value, solenoid valve A is turned ON by the TCM. As a result, the 1-2 shift valve is moved to the left side and

uncovers the port leading to the 2nd clutch, and the 2nd clutch is engaged.

Fluid flows by way of:

Hydraulic pressure also flows to the 1st clutch. However no power is transmitted through of the one-way clutch.

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

3. 3rd Gear

The flow of fluid to the 1-2, 2-3, and 3-4 shift valves is the same as in 2nd gear. As the speed of the vehicle reaches the

prescribed value, shift control solenoid valve B is turned OFF (Shift control solenoid valve A remains ON). The 2-3 shift

valve is then moved to the left side, uncovering the fluid port leading to the 3rd clutch. Since the 3-4 shift valve is

moved to the right side to cover the fluid port to the 4th clutch, the 3rd clutch is engaged.

Fluid flows by way of:

Hydraulic pressure also flows to the 1st clutch. However no power is transmitted through of the one-way clutch as in

2nd gear.

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

4. 4th Gear

The flow of fluid to the 1-2, 2-3, and 3-4 shift valves is the same as in 3rd gear. When the speed of the vehicle reaches

the prescribed valve, shift control solenoid valve A is turned OFF (Shift control solenoid valve B remains OFF). As this

takes place, the 3-4 shift valve is moved to the left side and uncovers the fluid port leading to the 4th clutch. Since the

1-2 and 2-3 shift valves are kept on the left side, the fluid flows through the 4th clutch, and power is transmitted

through the 4th clutch.

Fluid flows by way of:

Hydraulic pressure also flows to the 1st clutch. However no power is transmitted through of the one-way clutch as in

2nd and 3rd gear.

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