Subaru Legacy III (2000-2003 year). Manual - part 581

AT-58

AUTOMATIC TRANSMISSION (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)

E: DTC 33 FRONT VEHICLE SPEED SENSOR

DIAGNOSIS:
• The vehicle speed signal is abnormal.
• The circuit in combination meter is faulty.
• The harness connector between TCM and vehicle speed sensor is in short or open.
TROUBLE SYMPTOM:
• Erroneous idling.
• Engine stalls.
• Poor driving performance.

AT-59

AUTOMATIC TRANSMISSION (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)

WIRING DIAGRAM:

AT-00779

i10

B36

i1

17

18

B18

C17

E4

H6

H4

11

13

A10

B11

B53

T4

TCM

B54

A:

B55

B:

B56

C:

NT

TB

4
5
6

SHIELD AND
SENSOR GROUND
JOINT CONNECTOR

COMBINATION
METER

SPEEDOMETER

FRONT

VEHICLE SPEED

SENSOR

B54

B56

B55

B11

1 2

5

6 7

8

13

14 15

16

9 10

11 12

3 4

17 18

19 20

1 2 3 4

10 11 12
19 20 21

13

5 6

14 15

7

8

9

16

17

18

22

23

24

1 2 3 4

10 11 12
19 20 21

13

5 6

14 15

7

8

9

16

17

18

22

23

24

1 2 3 4

10 11 12
19 20 21

13

5 6

14 15

7

8

9

16

17

18

22

23

24

i10

1 2 3 4 5 6 7

8 9 10 11 12 13 14

15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30

1 2 3 4 5 6 7 8 9 10 11 12

B53

B36

B4 B5 B6

A4 A5 A6

C5 C6

F6

D4 D5 D6

F1

H1

C4

G6

G1

C2

K1

M1 M2

K6

L1

D1 D2

A1 A2
B1 B2

I6

J6

L2

I1

J1

H6

M4 M5 M6

L4 L5 L6 

N5 N6

O4 O5 O6

N4

P4 P5

N2

O1 O2

P1 P2

N3

O3

P3

P6

A3

B3

C3

E4 E5 E6

E1 E2

: EXCEPT 3.0L MODEL 
  AND TURBO MODEL 

: 3.0L MODEL 
  AND TURBO MODEL

H4

H6

B53

1 2 3 4 5 6

: NON-TURBO MODEL

NT

: TURBO  MODEL

TB

: NT

: TB

1
2
3

AT-60

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 transmission connector.

Connector & terminal

(B55) No. 18 — (B11) No. 17:

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 
and transmission connector.

Connector & terminal

(B54) No. 10 — (B11) No. 18:

Is the measured value less than the specified 
value?

1 

Ω

Go to step 3.

Repair open circuit 
in harness 
between TCM and 
transmission con-
nector, and poor 
contact in cou-
pling connector.

3

CHECK HARNESS CONNECTOR BETWEEN 
TCM AND TRANSMISSION.
Measure resistance of harness between TCM 
and transmission connector.

Connector & terminal

(B54) No. 10 — Chassis ground:

Does the measured value exceed the specified 
value?

1 M

Ω

Go to step 4.

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

4

CHECK HARNESS CONNECTOR BETWEEN 
TCM AND TRANSMISSION.
Measure resistance of harness between TCM 
and transmission connector.

Connector & terminal

(B55) No. 18 — Chassis ground:

Does the measured value exceed the specified 
value?

1 M

Ω

Go to step 5.

Repair short circuit 
in harness 
between TCM and 
transmission con-
nector, and poor 
contact in cou-
pling connector.

5

CHECK FRONT VEHICLE SPEED SENSOR.
Measure resistance between transmission 
connector receptacle's terminals.

Connector & terminal

(T4) No. 17 — No. 18:

Is the measured value within the specified 
range?

450 — 650 

Ω

Go to step 6.

Replace front vehi-
cle speed sensor. 
<Ref. to AT-54, 
Front Vehicle 
Speed Sensor.>

6

PREPARE OSCILLOSCOPE.
Do you have oscilloscope?

Oscilloscope is available.

Go to step 9.

Go to step 7.

7

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

Subaru Select Monitor is avail-
able.

Go to step 10.

Go to step 8.

AT-61

AUTOMATIC TRANSMISSION (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)

8

CHECK INPUT SIGNAL FOR TCM.
1) Connect all connectors.
2) Lift-up or raise the vehicle and place safety 

stands.

NOTE:

Raise all wheels off floor.

3) Start the engine and set vehicle in 20 km/h 

(12 MPH) condition.

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.>

4) Measure voltage between TCM connector 

terminals.

Connector & terminal

(B55) No. 18 (+) — (B54) No. 10 (

−−−−

):

Does the measured value exceed the spec-
ified value?

AC 1 V

Even if “POWER” 
indicator lights up, 
the circuit has 
returned to a nor-
mal condition at 
this time. A tempo-
rary poor connec-
tor or harness may 
be the case. 
Repair harness or 
connector in the 
front vehicle speed 
sensor circuit.

Go to step 11.

9

CHECK FRONT VEHICLE SPEED SENSOR 
USING OSCILLOSCOPE.
1) Connect all connectors.
2) Lift-up the vehicle and place safety stand.

NOTE:

Raise all wheels off ground.

3) Set oscilloscope to TCM connector termi-

nals.

Connector & terminal

Positive probe; (B55) No. 18
Ground; (B54) No. 10

4) Start the engine, and drive the wheels 

slowly.

NOTE:

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

5) Measure signal voltage indicated on oscillo-

scope.
Does the measured value exceed the spec-
ified value?

AC 1 V

Even if “POWER” 
indicator lights up, 
the circuit has 
returned to a nor-
mal condition at 
this time. A tempo-
rary poor connec-
tor or harness may 
be the case. 
Repair harness or 
connector in the 
front vehicle speed 
sensor circuit.

Go to step 11.

Step

Value

Yes

No