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

(

)