Subaru Legacy III (2000-2003 year). Service manual — part 591

AT-98

AUTOMATIC TRANSMISSION (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)

6

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

sion.

2) Lift-up the vehicle and place safety stand.

NOTE:

Raise all wheels off ground.

3) 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.

4) Move selector lever to “D” and slowly

increase vehicle speed to 75 km/h (47
MPH). Wheels will lock-up.

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.>

5) Measure voltage between TCM connector

and chassis ground.

Connector & terminal

(B54) No. 7 (+) — Chassis ground (

−−−−

):

Does the measured value exceed the spec-
ified value?

8.5 V

Go to step 7.

Go to step 10.

7

CHECK OUTPUT SIGNAL EMITTED FROM
TCM.
1) Return the engine to idling speed and move

select lever to “N”.

2) Measure voltage between TCM connector

and chassis ground.

Connector & terminal

(B54) No. 7 (+) — Chassis ground (

−−−−

):

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

0.5 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 TCM and
transmission.

Go to step 10.

Step

Value

Yes

No

AT-99

AUTOMATIC TRANSMISSION (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)

8

CHECK OUTPUT SIGNAL EMITTED FROM
TCM USING SUBARU SELECT MONITOR.
1) Connect connectors to TCM and transmis-

sion.

2) Lift-up the vehicle and place safety stand.

NOTE:

Raise all wheels off ground.

3) Connect Subaru Select Monitor to data link

connector.

4) Start the engine, and turn Subaru Select

Monitor switch to ON.

5) 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.

6) Read data of lock-up duty solenoid using

Subaru Select Monitor.

•Lock-up duty solenoid is indicated in “%”.
7) Move selector lever to “D” and slowly

increase vehicle speed to 75 km/h (47
MPH). Wheels will lock-up.

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.>

Is lock-up duty solenoid data the specified
value?

95%

Go to step 9.

Go to step 10.

9

CHECK OUTPUT SIGNAL EMITTED FROM
TCM USING SUBARU SELECT MONITOR.
1) Return the engine to idling speed and move

selector lever to “N”.

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) Read lock-up solenoid data using Subaru

Select Monitor.
Is lock-up solenoid data value the specified
value?

5%

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 TCM and
transmission.

Go to step 10.

10

CHECK POOR CONTACT.
Is there poor contact in lock-up duty solenoid
circuit?

There is poor contact.

Repair poor con-
tact.

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

Step

Value

Yes

No

AT-100

AUTOMATIC TRANSMISSION (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)

11

CHECK LOCK-UP DUTY SOLENOID (IN
TRANSMISSION).
1) Remove transmission connector from

bracket.

2) Drain automatic transmission fluid.

CAUTION:

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

3) Remove oil pan, and disconnect connector

from lock-up duty solenoid.

4) Measure resistance between lock-up duty

solenoid connector and transmission
ground.

Terminal

No. 1 — Transmission ground:

Is the measured value within the specified
range?

10 — 17

Ω

Go to step 12.

Replace lock-up
duty solenoid.
<Ref. to AT-67,
Shift Solenoids,
Duty Solenoids
and ATF Temper-
ature Sensor.>

12

CHECK HARNESS CONNECTOR BETWEEN
LOCK-UP DUTY SOLENOID AND TRANS-
MISSION.
Measure resistance of harness between lock-
up duty solenoid and transmission connector.

Connector & terminal

(T4) No. 13 — (AT3) No. 1:

Is the measured value less than the specified
value?

1

Ω

Go to step 13.

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

13

CHECK HARNESS CONNECTOR BETWEEN
LOCK-UP DUTY SOLENOID AND TRANS-
MISSION.
Measure resistance of harness between trans-
mission connector and transmission ground.

Connector & terminal

(T4) No. 13 — 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 lock-up
duty solenoid and
transmission.

Repair short circuit
in harness
between lock-up
duty solenoid and
transmission con-
nector.

Step

Value

Yes

No

AT-101

AUTOMATIC TRANSMISSION (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)

MEMO: