Subaru Legacy III (2000-2003 year). Manual - part 588

AT-86

AUTOMATIC TRANSMISSION (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)

5

CHECK OUTPUT SIGNAL EMITTED FROM 
TCM.
1) Move selector lever to “D”, and slowly 

increase vehicle speed to 65 km/h (40 
MPH).

NOTE:

The speed difference between front and rear
wheels may light the ABS warning light, but this
indicates no malfunction. When AT control di-
agnosis is finished, perform the ABS memory
clearance procedure of on-board diagnostics
system. <Ref. to ABS-22, Clear Memory
Mode.> or <Ref. to VDC-25, Clear Memory
Mode.>

2) Measure voltage between TCM connector 

and chassis ground.

Connector & terminal

(B54) No. 16 (+) — Chassis ground (

−−−−

):

Does the measured value exceed the spec-
ified value?

9 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-
tact in the trans-
mission.

Go to step 6.

6

CHECK POOR CONTACT.
Is there poor contact in 2-4 brake timing sole-
noid circuit?

There is poor contact.

Repair poor con-
tact.

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

7

CHECK 2-4 BRAKE TIMING SOLENOID (IN 
TRANSMISSION).
1) Remove transmission connector from 

bracket.

2) Lift-up or raise the vehicle and support with 

safety stand.

NOTE:

Raise all wheels off ground.

3) Drain automatic transmission fluid.

CAUTION:

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

4) Remove oil pan, and disconnect connector 

from 2-4 brake timing solenoid.

5) Measure resistance between 2-4 brake tim-

ing solenoid connector and transmission 
ground.

Terminal

No. 1 — Transmission ground:

Is the measured value within the specified 
range?

10 — 16 

Ω

Go to step 8.

Replace 2-4 brake 
timing solenoid. 
<Ref. to AT-67, 
Shift Solenoids, 
Duty Solenoids 
and ATF Temper-
ature Sensor.>

8

CHECK HARNESS CONNECTOR BETWEEN 
2-4 BRAKE TIMING SOLENOID AND 
TRANSMISSION.
Measure resistance of harness between 2-4 
brake timing solenoid and transmission con-
nector.

Connector & terminal

(AT8) No. 1 — (T4) No. 4:

Is the measured value less than the specified 
value?

1 

Ω

Go to step 9.

Repair open circuit 
in harness 
between 2-4 brake 
timing solenoid 
and transmission 
connector.

Step

Value

Yes

No

AT-87

AUTOMATIC TRANSMISSION (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)

9

CHECK HARNESS CONNECTOR BETWEEN 
2-4 BRAKE TIMING SOLENOID AND 
TRANSMISSION.
Measure resistance of harness between 2-4 
brake timing solenoid connector and transmis-
sion ground.

Connector & terminal

(T4) No. 4 — 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 2-4 brake 
timing solenoid 
and transmission.

Repair short circuit 
harness between 
2-4 brake timing 
solenoid and 
transmission con-
nector.

Step

Value

Yes

No

AT-88

AUTOMATIC TRANSMISSION (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)

M: DTC 75 LINE PRESSURE DUTY SOLENOID

DIAGNOSIS:
Output signal circuit of line pressure 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. 9 — (B11) No. 5:

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. 9 — 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-00587

 

9

B54

B11

AT2

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

LINE

PRESSURE

DUTY

SOLENOID

5

AT-89

AUTOMATIC TRANSMISSION (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)

3

CHECK LINE PRESSURE DUTY SOLENOID.
Measure resistance between transmission 
connector receptacle's terminals.

Terminal

(T4) No. 5 — No. 16:

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. 9 (+) — 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. 9 (+) — 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 transmis-
sion.

Go to step 9.

Step

Value

Yes

No