AT - A4AF3. Automatic Transaxle

Type
A : Automatic
M : Manual

② : Speed
3 : 3rd speed
4 : 4th speed
5 : 5th speed
6 : 6th speed

④ : Drive type
F : Front
R : RR
4 : 4WD

⑤ : Development sequence 1,2,3,…

Model code

AT - A4AF3

Front Clutch R/C: Rear Clutch E/C: End Clutch K/D: Kickdown Brake L&R: Low & Reverse Brake OWC: One Way Clutch

Operating elements

AT - A4AF3

clutch

One way clutch

Kick-down brake

Low & Reverse brake

Operating elements

AT - A4AF3

Planetary carrier

clutch

Forward sun gear

Transfer drive gear

Idler gear

Transfer driven gear

Rear clutch

One-way clutch

Annulus gear (Ring gear)

Power flow

AT - A4AF3

What if OWC is broken or installed wrong direction?
Is engine brake is available ?
Does vehicle pull back?

Input & Moving parts

Output

sun gear

Rear clutch

Long pinion

Annulus gear

Low-reverse brake

Power flow

AT - A4AF3

Is engine brake is available ?
Does vehicle pull back?

Input & Moving parts

Output

Stationary parts

brake

Short pinion

Forward sun gear

Kickdown brake

Annulus gear

Rear clutch

Long pinion

Power flow

AT - A4AF3

Does vehicle pull back?

Input & Moving parts

Output

Stationary parts

clutch (Preparation for 4th gear)

Forward sun gear

Carrier

End clutch

Annulus gear

Reverse sun gear

Rear clutch

Front clutch

Power flow

AT - A4AF3

Does end clutch deliver power ?
What if end clutch cannot operate? Vehicle can move at 3rd gear?
What is the purpose of end clutch engagement at 3rd gear?

Input & Moving parts

Output

Stationary parts

for preparing 4th gear engagement.
What if end clutch cannot operate? Vehicle can move at 3rd gear? ? Yes, vehicle can have 3rd gear without end clutch engagement.
What is the purpose of end clutch engagement at 3rd gear? ? End clutch is powered for preparing 4th gear engagement.

Power flow

AT - A4AF3

clutch

Long pinion

Carrier

Annulus gear

Reverse sun gear

Power flow

AT - A4AF3

Input & Moving parts

Output

Stationary parts

gear

Carrier

Annulus gear

Long pinion

Power flow

AT - A4AF3

Input & Moving parts

Output

Stationary parts

in.)
? adjusted by thickness of _____________. also replace ______________ located between the oil pump and front clutch.

; Find correct pair of thrust races (metal) and thrust washers (fiber) from following table.

AT - A4AF3

race and #1 thrust washer.

Measured endplay : ___________ mm
Standard endplay : ___________ mm

1. Application : A4AF3
2. Objectives
- To measure input shaft endplay
- To adjust the endply correctly by selecting proper race/washer
3. Required materials
- AT for overhaul
- Dial gauge
4. Procedure
- Measure input shaft endplay and write it down before overhaul.
- Overhaul the AT
- If the endplay is out of spec., select a proper #1 thrust race, #3 thrust washer when assemly.
- Measure the input shaft endplay after AT assembly.
5. Time to complete : 15 minutes
6. Reference : AT 2005 overhaul manual (ATMS-EG4DA)

Input shaft end play

AT - A4AF3

endplay) + Thickness of old part = ( ____________ mm - ____________ mm) + ____________ mm = ___________ mm = ________ t
#1 thrust washer selection : ___________ t

Input shaft end play

AT - A4AF3

Measure the input shaft endplay after AT assembly : ___________ mm

1. Application : A4AF3
2. Objectives
- To measure input shaft endplay
- To adjust the endply correctly by selecting proper race/washer
3. Required materials
- AT for overhaul
- Dial gauge
4. Procedure
- Measure input shaft endplay and write it down before overhaul.
- Overhaul the AT
- If the endplay is out of spec., select a proper #1 thrust race, #3 thrust washer when assemly.
- Measure the input shaft endplay after AT assembly.
5. Time to complete : 15 minutes
6. Reference : AT 2005 overhaul manual (ATMS-EG4DA)

End play : 0.4 ~ 0.6 mm (Adjusted by snap ring)

Bushing (for Cerato, before Nov. 07. 2004)

AT - A4AF3

Niddle roller bearing

[Case study] Incorrect gear ratio (4th gear)
: Abnormal busing worn-out causes poor oil
pressure supply to F/C.

Front clutch pressure

gear
End play : 0.7 ~ 0.9 mm (Adjusted by snap ring)
Centrifugal balance chamber applied
4 missing tooth of discs

Centrifugal balance chamber

Piston

Piston chamber

AT - A4AF3

Rear clutch pressure

carrier
End play : 0.4 ~ 0.65 mm (Adjusted by snap ring)

AT - A4AF3

hold reverse sun gear

[Installation of the Kickndown Brake]

AT - A4AF3

contact point

AT - A4AF3

Kick-down piston

Piston rod

gear
DTC: None
Cause: Kickdown brake

■ Case Study

Kick down brake adjustment

AT - A4AF3

and loosen the adjust screw (2 times, Torque : 5Nm, 50kgcm)

AT - A4AF3

* Adjustment procedure

the starting point and release the adjust screw (3 · 1/3 turn)

Starting point

Kick down brake adjustment

AT - A4AF3

* Adjustment procedure

nut. Torque : 20Nm (200kgcm)

carrier
End play : 0.675 ~ 0.987 mm (Adjusted by pressure plate)

Hydraulic pressure

LR brake pision

Center support

Wave spring

[Case study] R range shift shock ?broken wave spring

AT - A4AF3

proper endplay)

B2 actuation point (delayed:wave spring+proper end play)

* C1 : Front Clutch B2 : Low & Reverse Brake

Low & Reverse brake

AT - A4AF3

sun gear

Carrier

One way clutch

Service Point

AT - A4AF3

N→D, D→N.
2) To prevent R/C slip.

Rear clutch accumulator

AT - A4AF3

switch

OD OFF switch

Kick down switch

Brake switch

PCM

Inputs & Outputs

AT - A4AF3

OD OFF Lamp

Dashboard range signal (P,R,N,D & 2,L(PWM))

MIL (EUR, NA), (ON at 2 D/C)

215~275Ω (20˚C)

Input speed sensor (PG-A)

AT - A4AF3

speed.
Sensor resistance : 215~275Ω (20˚C)

AT - A4AF3

is 2.5V.

- A4AF3

MIL)

AT - A4AF3

cltuch operation (brake applied ? damper clutch off)
Output speed sensor failure detection (stall test detection)

changes according to ATF temperature
Damper clutch control : damper clutch On/Off control according to ATF temperature
High temperature control : performs different shift pattern when ATF temperature is too high (115 ℃)

AT - A4AF3

open]

[Oil temperature-failsafe]

on , OTS short to Battery

to Battery

display on the clutster]

Duty at 2 range : 75 %
Duty at L range : 87 %

(O/D ON) : 1st ?? 4th - D (O/D OFF) : 1st ?? 3rd ? 4th - 2 : 1st ?? 2nd ?3rd t - L L 1st ? 2nd

AT - A4AF3

understand the failsafe function of inhibitor switch
3. Required materials
- Vehicle with
4. Procedure
- Start engine and shift to ‘N or P’ position.
- Remove the 10A back-up fuse from the I/P fuse box.
- Check shift range on the cluster
- Check the shift position of Hi-scan
- Check the SCSV-ABC ON/OFF
- Write down the vehicle movement at R,D,2,L range
5. Time to complete : 5 minutes
6. Reference

Start engine and position shift lever to ‘N or P’ position
Remove the 10A back-up fuse from the I/P fusebox.

Back-up fuse

How is the shift range on the cluster?
Write down SCSV-ABC ON/OFF signal and gear position at D/2/L.

understand the failsafe function of inhibitor switch
3. Required materials
- Vehicle with
4. Procedure
- Start engine and shift to ‘R’ position.
- Remove the 10A back-up fuse from the I/P fuse box.
- Check shift range on the cluster
- Check the shift position of Hi-scan
- Check the SCSV-ABC ON/OFF
- Write down the vehicle movement at D,2,L range
5. Time to complete : 5 minutes
6. Reference

Start engine and position shift lever to ‘R’ position
Remove the 10A back-up fuse from the I/P fusebox.

Back-up fuse

How is the shift range on the cluster?
Write down SCSV-ABC ON/OFF signal and gear position at D/2/L.

understand the failsafe function of inhibitor switch
3. Required materials
- Vehicle with
4. Procedure
- Start engine and shift to 'D’ position.
- Remove the 10A back-up fuse from the I/P fuse box.
- Check shift range on the cluster
- Check the shift position of Hi-scan
- Check the SCSV-ABC ON/OFF
- Write down the vehicle movement at R,2,L range
5. Time to complete : 5 minutes
6. Reference

Start engine and position shift lever to ‘D’ position
Remove the 10A back-up fuse from the I/P fusebox.

Back-up fuse

How is the shift range on the cluster?
Write down SCSV-ABC ON/OFF signal and gear shifting at R/D/2/L.

understand the failsafe function of inhibitor switch
3. Required materials
- Vehicle with
4. Procedure
- Start engine and shift to ‘2’ position.
- Remove the 10A back-up fuse from the I/P fuse box.
- Check shift range on the cluster
- Check the shift position of Hi-scan
- Check the SCSV-ABC ON/OFF
- Write down the vehicle movement at R,D, L range
5. Time to complete : 5 minutes
6. Reference

Start engine and position shift lever to ‘2’ position
Remove the 10A back-up fuse from the I/P fusebox.

Back-up fuse

How is the shift range on the cluster?
Write down SCSV-ABC ON/OFF signal and gear shifting at R/D/L.

understand the failsafe function of inhibitor switch
3. Required materials
- Vehicle with
4. Procedure
- Start engine and shift to ‘L’ position.
- Remove the 10A back-up fuse from the I/P fuse box.
- Check shift range on the cluster
- Check the shift position of Hi-scan
- Check the SCSV-ABC ON/OFF
- Write down the vehicle movement at R,D,2 range
5. Time to complete : 5 minutes
6. Reference

Start engine and position shift lever to ‘L’ position
Remove the 10A back-up fuse from the I/P fusebox.

Back-up fuse

How is the shift range on the cluster?
Write down SCSV-ABC ON/OFF signal and gear shifting at R/D/2.

understand the failsafe function of inhibitor switch
3. Required materials
- Vehicle with
4. Procedure
- Remove the 10A back-up fuse from the I/P fuse box.
- start the engine and change sihft lever one by one
- Check shift range on the cluster
- Check the shift position of Hi-scan
- Check the SCSV-ABC ON/OFF
- Write down the vehicle movement at R,D,2,L range
5. Time to complete : 5 minutes
6. Reference

Back-up fuse

How is the shift range on the cluster? Write down SCSV-ABC ON/OFF signal and gear shifting at R/D/2.

Remove the 10A back-up fuse from the I/P fusebox.
Start engine and change shift lever to each position

: 2. Control elements
- PCSV-A : F/C, E/C, KD/B, LR/B
- PCSV-B : _______
- SCSV-C : _______

DCCSV

SCSV-B

SCSV-A

PCSV-A

PCSV-B

SCSV-C

Solenoid valves

SCSV : Shift Control Solenoid Valve
PCSV : Pressure Control Solenoid Valve
DCCSV : Damper Clutch Control Solenoid Valve

AT - A4AF3

PCSV: 2.9±0.3Ω - SCSV: 22.3±1.5Ω - DCCSV: 3Ω

DCCSV

SCSV-B

SCSV-A

PCSV-A

PCSV-B

SCSV-C

AT - A4AF3

at D3
Damper clutch operation at D4
Damper clutch operation at D3

1)

2)

3)

AT - A4AF3

D1
PCSV-A, PCSV-B operation at N-D
PCSV-A, PCSV-B operation at D range

3)

AT - A4AF3

range
SCSV-B, operation at D range
SCSV-C, operation at D range

1)

2)

3)

AT - A4AF3

ON (D12)

OFF (D34)

ON (D1)

ON (D4)

OFF (D23)

OFF (D12)

ON (D34)

3rd gear

4th gear

3rd ? 4th

dection
1) CAN-Low short to GND : DTC is not detected CAN communication with Scan tool is normal Current data from engine is normal
2) CAN-Low short to B+ : Communication error with Hi-scan DTC (U0001) is memorized
3) CAN-High short to GND or B+ : Communication error with Hi-scan DTC (U0001) is memorized
CAN interface required system (for Hi-scan communication) : Engine, AT, Immobilizer, Code saving
K-line communication system (without CAN interface) : ABS, ESP, A/Bag, TPMS

2) Are current data
incorrect ?

5. 1) Does symptom
occur intermittently ?
2) Does the big shock
happen ?

6. Electrical problem

7. Electrical

8. Hydraulic problem

9. Mechanical

10. Hydraulic

2. Basic inspection

No

Yes

No

Yes

Troubleshooting chart

AT - A4AF3

circuit & input sensor inspection

Actuator test

Driving test for flight record

Oil passage or valve body clean and check

Stall test

Hydraulic test

11. Identification of problem

12. Repair

13. Confirmation test

14. END

Troubleshooting chart

AT - A4AF3

R
Preparation - ATF temperature : 80 ~ 90 ℃ - Fluid level : at ‘HOT’ mark on the oil level gauge - Apply chocks to both rear wheels (or jack up the vehicle) - Connect Hi-scan pro and read ‘Engine speed’
Stall RPM : 2400 ~ 2800 rpm
Test result

ATF temperature : 80 ~ 90 ℃ - Fluid level : at ‘HOT’ mark on the oil level gauge - Jack up the vehicle - Install oil pressure gauge (09452-21500) and gauge adapter (09452-21001,2) on each pressure port - Read pressure value at idling or stall rpm
Standard value : Refer to workshop manual

AT - A4AF3

09452-2150

09452-21001

09452-21002

pressure

End clutch pressure
Low & reverse brake pressure
Damper clutch apply pressure
Damper clutch release pressure

(Preparation)

AT - A4AF3

sensor & adapter]

Pressure test (Preparation)

clutch pressure

N?D

D?N

Duty controlled

2.7V = 8.2kg/cm2

[R/C pressure & SCSV-A operation at N?D?N]

N?D

D?N

OFF

ON

AT - A4AF3

N?D?2?L]

[R/C pressure at L]

R/C pressure at L

PCSV-A duty control

range]

D/R pressure (1.1V=4.5kg/cm2)

D/A pressure (0.95V = 3.5kg/cm2)

D/A: Damper clutch apply
D/R: Damper clutch release

D/R pressure

D/A pressure

During acceleration

AT - A4AF3

sensor)

D/R pressure

D/A pressure

a

b

c

d

* a : D 1,2,3 gear b: D 3 gear with damper clutch engaged (lock-up) c: D3-4 up shift (no lock-up) d: D4 gear with lock-up

d

a

b

c

2~3.5 kg/cm2

AT - A4AF3

sensor)

D/R pressure

D/A pressure

a

b

D/R pressure

D/A pressure

* a : 2 range 1,2 gear
b: 2 range 2 gear with lock-up

2~3.5 kg/cm2

AT - A4AF3

control]

D range

N range

[At D range]

Servo apply pressure

D1

6.5 kg/cm2

D4

D3

8.5 kg/cm2

7 kg/cm2

SCSV-A

D1(ON)

D23(OFF)

D4(ON)

D2

AT - A4AF3

apply pressure)

8.5 kg/cm2

SCSV-A

2-1(ON)

2-2(OFF)

[At 2 range]

AT - A4AF3

range]

12 kg/cm2

a: PCSV-A duty control b: PCSV-A duty 0% (accleration)

a

b

Acceleration

17 kg/cm2

2 ? L

4~6 kg/cm2

Acceleration

PCSV-A duty control (32%)

AT - A4AF3