Subaru Legacy III (2000-2003 year). Manual - part 589

AT-90

AUTOMATIC TRANSMISSION (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)

7

CHECK OUTPUT SIGNAL EMITTED FROM 
TCM USING SUBARU SELECT MONITOR.
1) Connect connectors to TCM and transmis-

sion.

2) Connect Subaru Select Monitor to data link 

connector.

3) Start the engine, and turn Subaru Select 

Monitor switch to ON.

4) Warm-up the transmission until ATF tem-

perature is above 80

°

C (176

°

F).

NOTE:

If ambient temperature is below 0

°

C (32

°

F),

drive the vehicle until the ATF reaches its oper-
ating temperature.

5) Stop the engine and turn ignition switch to 

ON (engine OFF).

6) Move select lever to “N”.
7) Read data of line pressure duty solenoid 

using Subaru Select Monitor.

•Line pressure duty solenoid is indicated in 
“%”.
8) Throttle is fully closed.

Is line pressure duty solenoid data value 
the specified value?

100%

Go to step 8.

Go to step 9.

8

CHECK OUTPUT SIGNAL EMITTED FROM 
TCM USING SUBARU SELECT MONITOR.
1) Turn ignition switch to ON (Engine OFF).
2) Throttle is fully open.
3) Read line pressure duty solenoid data 

using Subaru Select Monitor.
Is line pressure duty solenoid data less 
than the specified value?

25%

Even if “POWER” 
indicator lights up, 
the circuit has 
returned to a nor-
mal condition at 
this time. A tempo-
rary poor contact 
of the connector or 
harness may be 
the cause. Repair 
harness or con-
nector in transmis-
sion.

Go to step 9.

9

CHECK POOR CONTACT.
Is there poor contact in line pressure duty sole-
noid circuit?

There is poor contact.

Repair poor con-
tact.

Replace TCM. 
<Ref. to AT-76, 
Transmission Con-
trol Module 
(TCM).>

10

CHECK LINE PRESSURE DUTY SOLENOID 
(IN TRANSMISSION).
1) Remove transmission connector from 

bracket.

2) Drain automatic transmission fluid.

CAUTION:

Do not drain the automatic transmission flu-
id until it cools down.

3) Remove oil pan, and disconnect connector 

from line pressure duty solenoid.

4) Measure resistance between line pressure 

duty solenoid connector and transmission 
ground.

Terminal

No. 1 — Transmission ground:

Is the measured value within the specified 
range?

2.0 — 4.5 

Ω

Go to step 11.

Replace line pres-
sure duty solenoid. 
<Ref. to AT-67, 
Shift Solenoids, 
Duty Solenoids 
and ATF Temper-
ature Sensor.>

Step

Value

Yes

No

AT-91

AUTOMATIC TRANSMISSION (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)

11

CHECK HARNESS CONNECTOR BETWEEN 
TRANSMISSION AND LINE PRESSURE 
DUTY SOLENOID.
Measure resistance of harness between line 
pressure duty solenoid and transmission con-
nector.

Connector & terminal

(T4) No. 5 — (AT2) No. 1:

Is the measured value less than the specified 
value?

1 

Ω

Go to step 12.

Repair open circuit 
in harness 
between line pres-
sure duty solenoid 
and transmission 
connector.

12

CHECK HARNESS CONNECTOR BETWEEN 
TRANSMISSION AND LINE PRESSURE 
DUTY SOLENOID.
Measure resistance of harness between trans-
mission connector and transmission ground.

Connector & terminal

(T4) No. 5 — Transmission ground:

Does the measured value exceed the specified 
value?

1 M

Ω

Even if “POWER” 
indicator lights up, 
the circuit has 
returned to a nor-
mal condition at 
this time. A tempo-
rary poor contact 
of the connector or 
harness may be 
the cause. Repair 
harness or con-
nector in line pres-
sure duty solenoid 
and transmission.

Repair short circuit 
in harness 
between line pres-
sure duty solenoid 
and transmission 
connector.

Step

Value

Yes

No

AT-92

AUTOMATIC TRANSMISSION (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)

N: DTC 76 2-4 BRAKE DUTY SOLENOID

DIAGNOSIS:
Output signal circuit of 2-4 brake duty solenoid is open or shorted.
TROUBLE SYMPTOM:
Excessive shift shock.
WIRING DIAGRAM:

Step

Value

Yes

No

1

CHECK HARNESS CONNECTOR BETWEEN 
TCM AND TRANSMISSION.
1) Turn ignition switch to OFF.
2) Disconnect connector from transmission 

and TCM.

3) Measure resistance of harness between 

TCM and transmission connector.

Connector & terminal

(B54) No. 18 — (B11) No. 9:

Is the measured value less than the speci-
fied value?

1 

Ω

Go to step 2.

Repair open circuit 
in harness 
between TCM and 
transmission con-
nector.

2

CHECK HARNESS CONNECTOR BETWEEN 
TCM AND CHASSIS GROUND.
Measure resistance of harness between TCM 
and chassis ground.

Connector & terminal

(B54) No. 18 — Chassis ground:

Does the measured value exceed the specified 
value?

1 M

Ω

Go to step 3.

Repair short circuit 
in harness 
between TCM and 
transmission con-
nector.

AT-00588

18

B54

B11

AT7

T4

TCM

TRANSMISSION

1

2

3

4

5

6

7

8

9

10 11 12 13 14 15

16

17

18

19 20 21

22 23

24

B54

B11

1

2

3 4

5

6 7

8

9

13

14 15

20

19

17

16

10

11 12

18

2-4

BRAKE DUTY

SOLENOID

9

AT-93

AUTOMATIC TRANSMISSION (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)

3

CHECK 2-4 BRAKE DUTY SOLENOID.
Measure resistance between transmission 
connector receptacle's terminals.

Terminal

(T4) No. 16 — No. 9:

Is the measured value within the specified 
range?

2.0 — 4.5 

Ω

Go to step 4.

Go to step 10.

4

PREPARE SUBARU SELECT MONITOR.
Do you have a Subaru Select Monitor?

Subaru Select Monitor is avail-
able.

Go to step 7.

Go to step 5.

5

CHECK OUTPUT SIGNAL EMITTED FROM 
TCM.
1) Connect all connectors.
2) Start the engine and warm-up the transmis-

sion until ATF temperature is above 80

°

C 

(176

°

F).

NOTE:

If ambient temperature is below 0

°

C (32

°

F),

drive the vehicle until the ATF reaches its oper-
ating temperature.

3) Turn ignition switch to ON (engine OFF).
4) Move select lever to “N”.
5) Throttle is fully closed.
6) Measure voltage between TCM connector 

and chassis ground.

Connector & terminal

(B54) No. 18 (+) — Chassis ground (

−−−−

):

Is the measured value within the specified 
range?

1.5 — 5.0 V

Go to step 6.

Go to step 9.

6

CHECK OUTPUT SIGNAL EMITTED FROM 
TCM.
1) Throttle is fully open.
2) Measure voltage between TCM connector 

and chassis ground.

Connector & terminal

(B54) No. 18 (+) — Chassis ground (

−−−−

):

Is the measured value less than the speci-
fied value?

1 V

Even if “POWER” 
indicator lights up, 
the circuit has 
returned to a nor-
mal condition at 
this time. A tempo-
rary poor contact 
of the connector or 
harness may be 
the cause. Repair 
harness or con-
nector in TCM and 
transmission.

Go to step 9.

Step

Value

Yes

No