Subaru Legacy III (2000-2003 year). Manual - part 592

AT-102

AUTOMATIC TRANSMISSION (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)

P: DTC 78 SPORT SHIFT SOLENOID

DIAGNOSIS:
Output signal circuit of SPORT shift solenoid is open or shorted.
TROUBLE SYMPTOM:
Engine brake is effective at D, 3, 2, ranges.
WIRING DIAGRAM:

AT-00663

14

TRANSMISSION

B54

TCM

AT10

SPORT SHIFT

SOLENOID

B54

1 2

7

8

9

5 6

3 4

10 11 12
19 20 21

13

14 15

16

17

18

22

23

24

T4

B11

8

B11

1 2

5

6 7

8

13

14 15

16

9 10

11 12

3 4

17 18

19 20

AT-103

AUTOMATIC TRANSMISSION (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)

Step

Value

Yes

No

1

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

mission.

3) Measure resistance of harness between 

TCM and SPORT shift solenoid connector.

Connector & terminal

(B54) No. 14 — (B11) No. 8:

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 TRANSMISSION.
Measure resistance of harness between TCM 
connector and chassis ground.

Connector & terminal

(B54) No. 14 — 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.

3

CHECK SPORT SHIFT SOLENOID.
Measure resistance between transmission 
connector terminals.

Connector & terminal

(T4) No. 8 — No. 16:

Is the measured value within the specified 
range?

10 — 16 

Ω

Go to step 4.

Go to step 7.

4

CHECK OUTPUT SIGNAL EMITTED FROM 
TCM.
1) Connect connectors to TCM and transmis-

sion.

2) Turn ignition switch to ON (engine OFF).
3) Measure voltage between TCM connector 

and chassis ground.

Connector & terminal

(B54) No. 14 (+) — Chassis ground (

−−−−

):

Does the measured value exceed the spec-
ified value?

9V

Go to step 5.

Go to step 6.

AT-104

AUTOMATIC TRANSMISSION (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)

5

CHECK OUTPUT SIGNAL EMITTED FROM 
TCM.
1) Turn ignition switch OFF.
2) Lift-up the vehicle and place safety stand.

NOTE:

Raise all wheels off ground.

3) Start engine, and warm transmission until 

ATF temperature becomes 80

°

C (176

°

F) or 

more.

4) Move select lever to SPORT shift mode.
5) Increase speed up to 25 km/h (16 MPH) at 

2nd.

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.>

6) Shift down to 1st speed, and effectively use 

engine brake.

7) Measure voltage between TCM connector 

and body ground when engine brake is 
effective.

Connector & terminal

(B54) No. 14 (+) — Chassis ground (

−−−−

):

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

1V

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 TCM.

Go to step 6.

6

CHECK POOR CONTACT.
Is there poor contact in SPORT shift solenoid 
circuit?

There is poor contact.

Repair poor con-
tact.

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

7

CHECK SHIFT SOLENOID 1 (IN TRANSMIS-
SION).
1) Remove transmission connector from 

bracket.

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

safety stand.

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 SPORT shift solenoid.

5) Measure resistance between SPORT shift 

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 SPORT 
shift solenoid. 
<Ref. to AT-67, 
Shift Solenoids, 
Duty Solenoids 
and ATF Temper-
ature Sensor.>

Step

Value

Yes

No

AT-105

AUTOMATIC TRANSMISSION (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)

8

CHECK HARNESS CONNECTOR BETWEEN 
SPORT SHIFT SOLENOID AND TRANSMIS-
SION.
Measure resistance of harness between shift 
solenoid 1 and transmission connector.

Connector & terminal

(AT10) No. 1 — (T4) No. 8:

Is the measured value less than the specified 
value?

1 

Ω

Go to step 9.

Repair open circuit 
in harness 
between SPORT 
shift solenoid and 
transmission con-
nector.

9

CHECK HARNESS CONNECTOR BETWEEN 
SPORT SHIFT SOLENOID AND TRANSMIS-
SION.
Measure resistance of harness between 
SPORT shift solenoid connector and transmis-
sion ground.

Connector & terminal

(T4) No. 8 — 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 SPORT 
shift solenoid and 
transmission.

Repair short circuit 
harness between 
SPORT shift sole-
noid and transmis-
sion connector.

Step

Value

Yes

No