Subaru Legacy III (2000-2003 year). Manual — part 580

AT-54

AUTOMATIC TRANSMISSION (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)

Step

Value

Yes

No

1

CHECK ENGINE GROUND TERMINALS.
Have engine ground terminals been tightened?

Engine ground terminals are
tightened correctly.

Go to step 2.

Tighten engine
ground terminals.

2

CHECK GROUND CIRCUIT OF ECM.
1) Turn ignition switch to OFF.
2) Disconnect connector from ECM.
3) Measure resistance of harness between

ECM and engine ground.

Connector & terminal

Non-TURBO without OBD model:

(B134) No. 27 — Engine ground:
(B134) No. 8 — Engine ground:
(B134) No. 7 — Engine ground:
(B136) No. 21 — Engine ground:
(B136) No. 22 — Engine ground:
(B135) No. 6 — Engine ground:

Non-TURBO with OBD model:

(B134) No. 7 — Engine ground:
(B134) No. 35 — Engine ground:
(B135) No. 21 — Engine ground:
(B136) No. 5 — Engine ground:
(B136) No. 16 — Engine ground:
(B136) No. 26 — Engine ground:
(B137) No. 14 — Engine ground:

TURBO model:

(B134) No. 7 — Engine ground:
(B134) No. 12 — Engine ground:
(B134) No. 15 — Engine ground:
(B134) No. 22 — Engine ground:
(B136) No. 8 — Engine ground:
(B136) No. 17 — Engine ground:
(B136) No. 18 — Engine ground:
(B137) No. 8 — Engine ground:
(B137) No. 9 — Engine ground:
(B84) No. 1 — Engine ground:

3.0 L model:

(B134) No. 7 — Engine ground:
(B134) No. 15 — Engine ground:
(B134) No. 22 — Engine ground:
(B136) No. 8 — Engine ground:
(B136) No. 17 — Engine ground:
(B136) No. 18 — Engine ground:
(B137) No. 8 — Engine ground:
(B137) No. 9 — Engine ground:
(B137) No. 21— Engine ground:
(B137) No. 31 — Engine ground:

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

5

Ω

Go to step 3.

Repair open circuit
in harness
between ECM
connector and
engine grounding
terminal.

AT-55

AUTOMATIC TRANSMISSION (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)

3

CHECK THROTTLE POSITION SENSOR.
1) Disconnect connector from throttle position

sensor.

2) Measure resistance between throttle posi-

tion sensor connector receptacle's termi-
nals.

Terminals

Except 3.0 L model and TURBO model:

No. 4 — No. 2:

3.0 L model:

No. 1 — No. 3:

TURBO model:

No. 1 — No. 2:

Is the measured value within the specified
range?

3.0 — 4.2 k

Ω

Go to step 4.

Replace throttle
position sensor.

4

CHECK THROTTLE POSITION SENSOR.
Measure resistance between throttle position
sensor connector receptacle's terminals.

Terminals

Except 3.0 L model:

No. 2 — No. 3:

3.0 L model:

No. 1 — No. 2:

Is the measured value within the specified
range?

0.35 — 0.5 k

Ω

Go to step 5.

Replace throttle
position sensor.

5

CHECK HARNESS CONNECTOR BETWEEN
TCM AND THROTTLE POSITION SENSOR.
1) Disconnect connector from TCM.
2) Measure resistance of harness between

TCM and throttle position sensor connec-
tor.

Connector & terminal

Except 3.0 L model:

(B55) No. 3 — (E13) No. 3:

3.0 L model:

(B55) No. 3 — (E13) No. 2:

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

1

Ω

Go to step 6.

Repair open circuit
in harness
between TCM and
throttle position
sensor connector,
and poor contact
in coupling con-
nector.

6

CHECK HARNESS CONNECTOR BETWEEN
TCM AND THROTTLE POSITION SENSOR.
Measure resistance of harness between TCM
and throttle position sensor connector.

Connector & terminal

Except 3.0 L model and TURBO model:

(B54) No. 2 — (E13) No. 4:

3.0 L model:

(B54) No. 2 — (E13) No. 3:

TURBO model:

(B54) No. 2 — (E13) No. 1:

Is the measured value less than the specified
value?

1

Ω

Go to step 7.

Repair open circuit
in harness
between TCM and
throttle position
sensor connector,
and poor contact
in coupling con-
nector.

7

CHECK HARNESS CONNECTOR BETWEEN
TCM AND THROTTLE POSITION SENSOR.
Measure resistance of harness between TCM
connector and chassis ground.

Connector & terminal

(B54) No. 3 — Chassis ground:

Does the measured value exceed the specified
value?

1 M

Ω

Go to step 8.

Repair short circuit
in harness
between TCM and
throttle position
sensor connector.

Step

Value

Yes

No

AT-56

AUTOMATIC TRANSMISSION (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)

8

CHECK HARNESS CONNECTOR BETWEEN
TCM AND THROTTLE POSITION SENSOR.
Measure resistance of harness between TCM
connector and chassis ground.

Connector & terminal

(B54) No. 2 — Chassis ground:

Does the measured value exceed the specified
value?

1 M

Ω

Go to step 9.

Repair short circuit
in harness
between TCM and
throttle position
sensor connector.

9

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

Connector & terminal

Non-TURBO without OBD model:

(B54) No. 3 — (B136) No. 17:

Non-TURBO with OBD model:

(B54) No. 3 — (B135) No. 13:

TURBO model:

(B54) No. 3 — (B135) No. 7:

3.0 L model:

(B54) No. 3 — (B135) No. 7:

Is the measured value less than the specified
value?

1

Ω

Go to step 10.

Repair open circuit
in harness
between TCM and
ECM connector.

10

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

Connector & terminal

Non-TURBO without OBD model:

(B54) No. 2 — (B136) No. 15:

Non-TURBO with OBD model:

(B54) No. 2 — (B135) No. 3:

TURBO model:

(B54) No. 2 — (B135) No. 9:

3.0 L model:

(B54) No. 2 — (B135) No. 9:

Is the measured value less than the specified
value?

1

Ω

Go to step 11.

Repair open circuit
in harness
between TCM and
ECM connector.

11

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

Subaru Select Monitor is avail-
able.

Go to step 14.

Go to step 12.

12

CHECK INPUT SIGNAL FOR TCM.
1) Connect connectors to TCM, throttle posi-

tion sensor and ECM.

2) Turn ignition switch to ON (engine OFF).
3) Close the throttle completely.
4) Measure voltage between TCM connector

and chassis ground.

Connector & terminal

(B54) No. 3 (+) — Chassis ground (

−−−−

):

Is the measured value within the specified
range?

0.2 — 1.0 V

Go to step 13.

Go to step 18.

13

CHECK INPUT SIGNAL FOR TCM.
1) Open the throttle completely.
2) Measure voltage between TCM connector

and chassis ground.

Connector & terminal

(B54) No. 3 (+) — Chassis ground (

−−−−

):

Is the measured value within the specified
range?

4.2 — 4.7 V

Go to step 16.

Go to step 18.

Step

Value

Yes

No

AT-57

AUTOMATIC TRANSMISSION (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)

14

CHECK INPUT SIGNAL FOR TCM USING
SUBARU SELECT MONITOR.
1) Connect connectors to TCM, throttle posi-

tion sensor and ECM.

2) Connect Subaru Select Monitor to data link

connector.

3) Turn ignition switch to ON (engine OFF).
4) Turn Subaru Select Monitor switch to ON.
5) Throttle fully closed.
6) Read data of throttle position sensor using

Subaru Select Monitor.

•Throttle position sensor input signal is indi-
cated.

Is throttle sensor data within the specified
range?

0.2 — 1.0 V

Go to step 15.

Go to step 18.

15

CHECK INPUT SIGNAL FOR TCM USING
SUBARU SELECT MONITOR.
Throttle fully open.

NOTE:

Must be changed correspondingly with acceler-
ator pedal operation (from “released” to “de-
pressed” position).

Is throttle sensor data within the specified
range?

4.2 — 4.7 V

Go to step 18.

Go to step 17.

16

CHECK INPUT SIGNAL FOR TCM (THROT-
TLE POSITION SENSOR POWER SUPPLY).
Measure voltage between TCM connector and
chassis ground.

Connector & terminal

(B54) No. 2 (+) — Chassis ground (

−−−−

):

Is the measured value within the specified
range?

4.8 — 5.3 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 throttle
position sensor cir-
cuit.

Go to step 18.

17

CHECK INPUT SIGNAL FOR TCM USING
SUBARU SELECT MONITOR (THROTTLE
POSITION SENSOR POWER SUPPLY).
Read data of throttle position sensor power
supply using Subaru Select Monitor.
•Throttle position sensor power supply voltage
is indicated.
Is the measured value within the specified
range?

4.8 — 5.3 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 throttle
position sensor cir-
cuit.

Go to step 18.

18

CHECK POOR CONTACT.
Is there poor contact in throttle position sensor
circuit?

There is poor contact.

Repair poor con-
tact.

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

Step

Value

Yes

No