AUTOMATIC TRANSAXLE HYDRAULIC CIRCUIT
NEUTRAL ＆ PARK
DRIVE (FIRST)
DRIVE (SECOND)
DRIVE (THIRD)
DRIVE (FOURTH)
REVERSE
HYDRAULIC CONTROL SYSTEM
MANUAL VALVE

Operation

Shift control solenoid valve

Position

A

B

C

1st gear

ON

ON

OFF

2nd gear

OFF

ON

OFF

3rd gear

OFF

OFF

ON

4th gear

ON

OFF

ON

Items

A4AF2

A4AF3

Pressure Control for SA, E/C

PCV + PCSV

PCV N-D V/v 1-2Shift V/v

PCV-A + PCSV-A

PCV-A, 1-2Shift V/v

Pressure Control for R/C

PCV + PCSV

PCV N-D V/v RCE V/v

PCV-B + Another Sol. V/v (PCSV-B)

PCV-B, RCE V/v (with accumulator)

Changed points :
-

N-D valve has been eliminated.

-

PCSV-B has been added for Rear clutch pressure control independently.

-

Mechanical accumulator has been adopted.

-

E/C release control : PCV-A, Switching of SA, E/C :CSV

-

Function

Switching the pressure of E/C and SA.

-

2nd. Gear

●

The 2nd. pressure is supplied to SA through CSV.

●

SCSV-C is OFF as well as 1st. gear.

-

2nd.→3rd. gear

●

SCSV-C maintains OFF as well as 2nd gear.

●

The E/C pressure from shift control valve is intercepted at the E/C valve during up-shifting from 2nd to 3rd gear.

●

SA pressure is supplied from 1-2 shift valve, but the front clutch and SR pressure is also supplied from the 2-3/4-3 shift valve, so the both SR and SA pressure will be set off.

-

3rd. gear

●

SCSV-C is changed from OFF to ON.

●

The E/C pressure is supplied from 1-2 shift valve at the CSV after finishing the up-shifting from 2nd to 3rd gear.

●

SA pressure is supplied from shift control valve, but the front clutch and SR pressure is also supplied from the 2-3/4-3 shift valve, so the both SR and SA pressure will be set off.

1.

Operating elements

Speed

R/C

E/C

K/D

4th.

-

O

O

2nd.

O

-

O

2.

Controls

A.

R/C engaging duty control

B.

E/C releasing duty control

C.

Continuous switching to SA

3.

Description

A.

R/C engaging duty control

B.

E/C releasing duty control

4→2 Skip shift only (SCSV-C ON)

When releasing the E/C clutch pressure, it is controlled by duty of PCSV-A only in case of 4→2 skip shift.

C.

Continuous switching to SA

-

From (SCV) to SA through (CSV)

1.

TCM fail when drive with 1st or 2nd speed.

Speed

F/C

R/C

E/C

K/D

1st.

O

2nd.

O

O

Fail

O

O

-

F/C, SR : from 2-3/4-3 shift valve

-

R/C : from PCV-B

-

SA : from 1-2 shift valve

2.

TCM fail when drive with 1st or 2nd speed.

Speed

F/C

R/C

E/C

K/D

1st.

O

2nd.

O

O

Fail

O

O

O

-

R/C, E/C, SA : Interlock

note
●

SA : Servo Apply pressure

●

F/C : Front Clutch pressure

●

R/C : Rear Clutch pressure

●

K/D : Kick Down

●

SCV : Shift Control Valve

●

CSV : Control Switch Valve

●

PCSV : Pressure Control Solenoid Valve

●

SCSV : Shift Control Solenoid Valve

●

PCV : Pressure Control Valve

●

RCEV : Rear Clutch Exhaust Valve

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