Subaru Legacy IV (2008 year). Service manual — part 695

4AT-128

Transmission Control Device

AUTOMATIC TRANSMISSION

4AT(diag)-2

Basic Diagnostic Procedure

AUTOMATIC TRANSMISSION (DIAGNOSTICS)

1. Basic Diagnostic Procedure

A: PROCEDURE

Step

Check

Yes

No

1

CHECK PRE-INSPECTION.
1) Ask the customer when and how the trouble
occurred using the interview check list. <Ref. to
4AT(diag)-4, Check List for Interview.>
2) Check the following items which may be
affecting the AT trouble.
• General inspection <Ref. to 4AT(diag)-5,
INSPECTION, General Description.>
• Disconnection of harness connector
• Visual check for harness damage
• Oil leakage
• Stall speed test <Ref. to 4AT-30, Stall Test.>
• Line pressure test <Ref. to 4AT-33, Line Pres-
sure Test.>
• Transfer clutch pressure test <Ref. to 4AT-34,
Transfer Clutch Pressure Test.>
• Time lag test <Ref. to 4AT-32, Time Lag
Test.>
• Road test <Ref. to 4AT-29, Road Test.>
• Inhibitor switch <Ref. to 4AT-46, Inhibitor
Switch.>

Is the item that is thought to
influence the AT problem work-
ing properly?

Go to step 2.

Repair or replace
each item.

2

CHECK ATF TEMPERATURE WARNING
LIGHT.
Start the engine and wait for 2 seconds or more.

Is the ATF temperature warning
light blinking?

Go to step 4.

Go to step 3.

3

CHECK ATF TEMPERATURE WARNING
LIGHT.
1) Turn the ignition switch to OFF.
2) Check the ATF temperature warning light.
<Ref. to 4AT(diag)-24, INSPECTION, AT OIL
TEMP Warning Light Display.>
3) Turn the ignition switch to ON and wait for at
least 2 seconds.
4) Start the engine.

Is the ATF temperature warning
light blinking?

Go to step 4.

Go to step 5.

4

CHECK DTC.
Display DTC.

NOTE:
If the communication function of Subaru Select
Monitor cannot be executed normally, check
the communication circuit. <Ref. to 4AT(diag)-
26, COMMUNICATION FOR INITIALIZING IM-
POSSIBLE, Diagnostic Procedure for Subaru
Select Monitor Communication.>

Is DTC displayed?

Go to step 6.

NOTE:
Record all DTC.

Go to step 5.

5

PERFORM GENERAL DIAGNOSTICS.
1) Inspect using “Diagnostic Procedure with-
out Diagnostic Trouble Code (DTC)”. <Ref. to
4AT(diag)-83, Diagnostic Procedure without
Diagnostic Trouble Code (DTC).>
2) Inspect using “General Diagnostic Table”.
<Ref. to 4AT(diag)-94, General Diagnostic
Table.>
3) Perform the Inspection Mode. <Ref. to
4AT(diag)-21, Inspection Mode.>
4) Display DTC.

Is DTC displayed?

Go to step 6.

Finish the diagno-
sis.

4AT(diag)-3

Basic Diagnostic Procedure

AUTOMATIC TRANSMISSION (DIAGNOSTICS)

6

PERFORM DIAGNOSIS.
1) Inspect using “Diagnostic Procedure with
Diagnostic Trouble Code (DTC)”. <Ref. to
4AT(diag)-32, Diagnostic Procedure with Diag-
nostic Trouble Code (DTC).>

NOTE:
For DTC table, refer to “List of Diagnostic Trou-
ble Code (DTC)”. <Ref. to 4AT(diag)-30, List of
Diagnostic Trouble Code (DTC).>
2) Repair the trouble cause.
3) Perform the Clear Memory Mode.
4) Perform the Inspection Mode. <Ref. to
4AT(diag)-21, Inspection Mode.>
5) Display DTC.

Is DTC displayed?

Inspect using
“Diagnostic Proce-
dure with Diagnos-
tic Trouble Code
(DTC)”. <Ref. to
4AT(diag)-32,
Diagnostic Proce-
dure with Diagnos-
tic Trouble Code
(DTC).>

Finish the diagno-
sis.

Step

Check

Yes

No

4AT(diag)-4

Check List for Interview

AUTOMATIC TRANSMISSION (DIAGNOSTICS)

2. Check List for Interview

A: CHECK

Check the following item when problem has occurred.

NOTE:
Use copies of this page for interviewing customers.

Customer’s name

Date of purchase

Date of repair

Transmission model

Transmission

V.I.N.

Odometer reading

km (miles)

Frequency

Continuous

Intermittent (

times a day)

Weather

Fine

Cloudy

Rainy

Snowy

Others

(

)

Place

Highland

Suburbs

Inner city

Uphill

Rough road

Others

(

)

Ambient air temperature

Hot

Warm

Cool

Cold

Vehicle speed

km/h (MPH)

AT warning light (ATF temperature
warning light)

Blinks continuously

Does not blink

Select lever position

P

R

N

D

SPORT mode

Driving condition

Not affected
At racing
While decelerating

At starting
When accelerating
While turning (

RH/

LH)

While idling
While cruising

SPORT mode

ON

OFF

Symptom

No up-shift

No down-shift

No kick down

Vehicle does not move (

Any position

Particular position)

Lock-up malfunction

Noise or vibration

Shift shock or slip

Select lever does not move

Others

(

)