Subaru Legacy III (2000-2003 year). Manual - part 604

AT-150

AUTOMATIC TRANSMISSION (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE FOR NO-DIAGNOSTIC TROUBLE CODE (DTC)

10

CHECK HARNESS CONNECTOR BETWEEN 
TCM AND SPORT SHIFT SWITCH.
1) Disconnect connector from TCM.
2) Measure resistance of harness between 

TCM connector and SPORT shift switch 
connector.

Connector & terminal

(B237) No. 5 — (B55) No. 15:

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

1 

Ω

Go to step 11.

Repair open circuit 
in harness 
between SPORT 
shift switch con-
nector and TCM 
connector and 
poor contact in 
coupling connec-
tor.

11

CHECK HARNESS CONNECTOR BETWEEN 
TCM AND SPORT SHIFT SWITCH.
1) Disconnect connector from TCM.
2) Measure resistance of harness between 

SPORT shift switch connector and chassis 
ground.

Connector & terminal

(B237) No. 5 — Chassis ground:

Does the measured value exceed the spec-
ified value?

1 M

Ω

Go to step 12.

Repair short circuit 
in harness 
between SPORT 
shift switch con-
nector and TCM 
connector.

12

CHECK INPUT SIGNAL FOR TCM.
1) Connect connector to TCM and SPORT 

shift switch.

2) Turn ignition switch to ON. (Engine is 

stopped.)

3) Move select lever to normal mode.
4) Measure signal voltage for TCM.

Connector & terminal

(B55) No. 15 (+) — Chassis ground (–):

Does the measured value exceed the spec-
ified value?

9 V

Go to step 13.

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

13

CHECK INPUT SIGNAL FOR TCM.
1) Move select lever to SPORT shift mode.
2) Measure signal voltage for TCM.

Connector & terminal

(B55) No. 15 (+) — Chassis ground (–):

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

1 V

Go to step 35.

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

14

CHECK SPORT SHIFT SWITCH GROUND 
LINE.
1) Turn ignition switch to OFF.
2) Disconnect connector from SPORT shift 

switch.

3) Measure resistance of harness between 

SPORT shift switch connector and chassis 
ground.

Connector & terminal

(B237) No. 6 — Chassis ground:

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

1 

Ω

Go to step 15.

Repair open circuit 
in harness 
between SPORT 
shift switch and 
chassis ground.

15

CHECK SPORT SHIFT SWITCH.
1) Measure resistance between SPORT shift 

switch terminals.

Connector & terminal

(B237) No. 6 — No. 2:

Does the measured value exceed the spec-
ified value?

1 M

Ω

Go to step 16.

Replace guide 
plate assembly.

Step

Value

Yes

No

AT-151

AUTOMATIC TRANSMISSION (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE FOR NO-DIAGNOSTIC TROUBLE CODE (DTC)

16

CHECK SPORT SHIFT SWITCH.
1) Move select lever to SPORT shift mode.
2) Measure resistance between SPORT shift 

switch terminals.

Connector & terminal

(B237) No. 6 — No. 2:

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

1 

Ω

Go to step 17.

Replace guide 
plate assembly.

17

CHECK HARNESS CONNECTOR BETWEEN 
TCM AND SPORT SHIFT SWITCH.
1) Disconnect connector from TCM.
2) Measure resistance of harness between 

TCM connector and SPORT shift switch 
connector.

Connector & terminal

(B237) No. 2 — (B55) No. 13:

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

1 

Ω

Go to step 18.

Repair open circuit 
in harness 
between SPORT 
shift switch con-
nector and TCM 
connector and 
poor contact in 
coupling connec-
tor.

18

CHECK HARNESS CONNECTOR BETWEEN 
TCM AND SPORT SHIFT SWITCH.
1) Disconnect connector from steering roll 

connector.

2) Measure resistance of harness between 

SPORT shift switch connector and chassis 
ground.

Connector & terminal

(B237) No. 2 — Chassis ground:

Does the measured value exceed the spec-
ified value?

1 M

Ω

Go to step 19.

Repair short circuit 
in harness 
between SPORT 
shift switch con-
nector and TCM 
connector.

19

CHECK INPUT SIGNAL FOR TCM.
1) Connect all connectors.
2) Turn ignition switch to ON. (Engine is 

stopped.)

3) Measure signal voltage for TCM.

Connector & terminal

(B55) No. 13 (+) — Chassis ground (–):

Does the measured value exceed the spec-
ified value?

9 V

Go to step 20.

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

20

CHECK INPUT SIGNAL FOR TCM.
1) Move select lever to shift up side.
2) Measure signal voltage for TCM.

Connector & terminal

(B55) No. 13 (+) — Chassis ground (–):

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

1 V

Go to step 35.

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

21

CHECK SPORT SHIFT SWITCH GROUND 
LINE.
1) Turn ignition switch to OFF.
2) Disconnect connector from SPORT shift 

switch.

3) Measure resistance of harness between 

SPORT shift switch connector and chassis 
ground.

Connector & terminal

(B237) No. 3 — Chassis ground:

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

1

 Ω

Go to step 22.

Repair open circuit 
in harness 
between SPORT 
shift switch and 
chassis ground.

Step

Value

Yes

No

AT-152

AUTOMATIC TRANSMISSION (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE FOR NO-DIAGNOSTIC TROUBLE CODE (DTC)

22

CHECK SPORT SHIFT SWITCH.
Measure resistance between SPORT shift 
switch terminals.

Connector & terminal

(B237) No. 3 — No. 1:

Does the measured value exceed the spec-
ified value?

1 M

Ω

Go to step 24.

Replace guide 
plate assembly.

23

CHECK SPORT SHIFT SWITCH.
1) Move select lever to SPORT shift mode.
2) Measure resistance between SPORT shift 

switch terminals.

Connector & terminal

(B237) No. 3 — No. 1:

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

1 

Ω

Go to step 24.

Replace guide 
plate assembly.

24

CHECK HARNESS CONNECTOR BETWEEN 
TCM AND SPORT SHIFT SWITCH.
1) Disconnect connector from TCM.
2) Measure resistance of harness between 

TCM connector and SPORT shift switch 
connector.

Connector & terminal

(B237) No. 1 — (B55) No. 2:

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

1 

Ω

Go to step 25.

Repair open circuit 
in harness 
between SPORT 
shift switch con-
nector and TCM 
connector and 
poor contact in 
coupling connec-
tor.

25

CHECK HARNESS CONNECTOR BETWEEN 
TCM AND SPORT SHIFT SWITCH.
1) Disconnect steering roll connector.
2) Measure resistance of harness between 

SPORT shift switch connector and chassis 
ground.

Connector & terminal

(B237) No. 1 — Chassis ground:

Does the measured value exceed the spec-
ified value?

1 M

Ω

Go to step 26.

Repair short circuit 
in harness 
between SPORT 
shift switch con-
nector and TCM 
connector.

26

CHECK INPUT SIGNAL FOR TCM.
1) Connect all connectors.
2) Turn ignition switch to ON. (Engine is 

stopped.)

3) Measure signal voltage for TCM.

Connector & terminal

(B55) No. 2 (+) — Chassis ground (–):

Does the measured value exceed the spec-
ified value?

9 V

Go to step 27.

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

27

CHECK INPUT SIGNAL FOR TCM.
1) Move select lever to shift up side.
2) Measure signal voltage for TCM.

Connector & terminal

(B55) No. 2 (+) — Chassis ground (–):

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

1 V

Go to step 35.

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

Step

Value

Yes

No

AT-153

AUTOMATIC TRANSMISSION (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE FOR NO-DIAGNOSTIC TROUBLE CODE (DTC)

28

CHECK ground circuit of steering shift 
switch.
1) Turn ignition switch OFF.
2) Disconnect connector from steering roll 

connector.

3) Measure resistance of harness between 

steering roll connector and chassis ground.

Connector & terminal

(B68) No. 5 — Chassis ground:

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

1 

Ω

Go to step 29.

Repair open circuit 
between steering 
roll connector and 
body ground.

29

CHECK steering shift switch.
Measure resistance between steering roll con-
nector terminals.

Connector & terminal

(B68) No. 5 — No. 2:

Does the measured value exceed the the 
specified value?

1 M

Ω

Go to step 30.

Replace steering 
roll connector or 
steering shift 
switch. Repair 
connector poor 
contact.

30

CHECK steering shift switch.
1) Press steering shift switch + side and hold 

it.

2) Measure resistance between terminals 

between steering shift switch.

Connector & terminal

(B68) No. 5 — No. 2:

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

1 

Ω

Go to step 31.

Replace steering 
roll connector or 
steering shift 
switch. Repair 
connector poor 
contact.

31

CHECK harness connector between TCM 
and Steering roll connector.
1) Disconnect connector from TCM.
2) Measure harness resistance between TCM 

connector and steering roll connector.

Connector & terminal

(B55) No. 13 — (B68) No. 2:

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

1 

Ω

The circuit is 
returned to a nor-
mal condition. 
Temporary poor 
contact of the har-
ness may be the 
case. Repair poor 
contact of steering 
roll connector and 
steering shift 
switch harness or 
connector.

Repair poor con-
tact or harness 
disconnection 
between connec-
tors of TCM con-
nector and 
steering roll con-
nector 

32

CHECK Steering shift switch.
1) Turn ignition switch to OFF.
2) Disconnect connector from steering roll 

connector.

3) Measure resistance value between steering 

roll connectors.

Connector & terminal

(B68) No. 5 — No. 3:

Does the measured value exceed the spec-
ified value?

1 

ΜΩ

Go to step 33.

Replace steering 
roll connector or 
steering shift 
switch. Repair 
connector poor 
contact.

33

CHECK Steering shift switch.
1) Press steering shift switch + side and hold 

it.

2) Measure resistance between terminals of 

steering shift switch.

Connector & terminal

(B68) No. 5 — No. 3:

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

1 

Ω

Go to step 34.

Replace steering 
roll connector or 
steering shift 
switch. Repair 
connector poor 
contact.

Step

Value

Yes

No