2004 SUBARU FORESTER check engine

4AT(H4SO)-73
AUTOMATIC TRANSMISSION (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
8 CHECK OUTPUT SIGNAL EMITTED FROM
TCM USING SUBARU SELECT MONITOR.
1) Turn the ignition switch to ON (engine
OFF).
2) Throttle is fully open.
3) Read the data of 2-4 brake duty solenoid
using Subaru Select Monitor.Is the value less than 25%? Even if the
POWER indicator
light was blinking,
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
the harness or
connector in TCM
and transmission.Go to step 9.
9 CHECK POOR CONTACT.Is there poor contact in 2-4
brake duty solenoid circuit?Repair the poor
contact.Replace the TCM.
Transmission Con-
trol Module
(TCM).>
10 CHECK 2-4 BRAKE DUTY SOLENOID (IN
TRANSMISSION).
1) Remove the transmission connector from
bracket.
2) Drain the ATF.
CAUTION:
Do not drain the ATF until it cools down.
3) Remove the oil pan, and disconnect con-
nector from 2-4 brake duty solenoid.
4) Measure the resistance between 2-4 brake
duty solenoid connector and transmission
ground.
Te r m i n a l s
No. 1 — Transmission ground:Is the resistance 2.0 — 4.5 Ω? Go to step 11.Replace the 2-4
brake duty sole-
noid. 71, Shift Sole-
noids, Duty Sole-
noids and ATF
Temperature Sen-
sor.>
11 CHECK HARNESS CONNECTOR BETWEEN
TRANSMISSION AND 2-4 BRAKE DUTY SO-
LENOID.
Measure the resistance of harness between 2-
4 brake duty solenoid and transmission con-
nector.
Connector & terminal
(T4) No. 9 — (AT7) No. 1:Is the resistance less than 1
Ω?Go to step 12.Repair the open
circuit in harness
between 2-4 brake
duty solenoid and
transmission con-
nector.
12 CHECK HARNESS CONNECTOR BETWEEN
TRANSMISSION AND 2-4 BRAKE DUTY SO-
LENOID.
Measure the resistance of harness between
transmission connector and transmission
ground.
Connector & terminal
(T4) No. 9 — Transmission ground:Is the resistance more than 1
MΩ?Even if the
POWER indicator
light was blinking,
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
the harness or
connector in line
pressure duty
solenoid and
transmission.Repair the short
circuit in harness
between 2-4 brake
duty solenoid and
transmission con-
nector. Step Check Yes No

4AT(H4SO)-75
AUTOMATIC TRANSMISSION (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step Check Yes No
1 CHECK DTC.Do multiple DTCs appear in
the on-board diagnostics test
mode?Go to another
DTC.Go to step 2.
2 CHECK HARNESS CONNECTOR BETWEEN
TCM AND TRANSMISSION.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from TCM and
transmission.
3) Measure the resistance of harness
between TCM and transmission connector.
Connector & terminal
(B54) No. 7 — (B11) No. 13:Is the resistance less than 1
Ω?Go to step 3.Repair the open
circuit in harness
between TCM and
transmission con-
nector.
3 CHECK HARNESS CONNECTOR BETWEEN
TCM AND TRANSMISSION.
Measure the resistance of harness connector
between TCM and chassis ground.
Connector & terminal
(B54) No. 7 — Chassis ground:Is the resistance more than 1
MΩ?Go to step 4.Repair the short
circuit in harness
between TCM and
transmission con-
nector.
4 CHECK LOCK-UP DUTY SOLENOID.
Measure the resistance between transmission
connector receptacle’s terminals.
Connector & terminal
(T4) No. 13 — No. 16:Is the resistance 10 — 17 Ω? Go to step 5.Go to step 11.
5 PREPARE SUBARU SELECT MONITOR.Do you have a Subaru Select
Monitor?Go to step 8.Go to step 6.
6 CHECK OUTPUT SIGNAL EMITTED FROM
TCM.
1) Connect the connectors to TCM and trans-
mission.
2) Lift-up the vehicle and place rigid rack.
N
OTE:
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 ATF reaches its operating
temperature.
4) Move the selector lever to “D” range and
slowly increase vehicle speed to 60 km/h (37
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 diag-
nosis is finished, perform the ABS memory
clearance procedure of on-board diagnostics
system. Mode.>
5) Measure the voltage between TCM con-
nector and chassis ground.
Connector & terminal
(B54) No. 7 (+) — Chassis ground (
−):Is the voltage more than 8.5 V? Go to step 7.Go to step 10.

4AT(H4SO)-76
AUTOMATIC TRANSMISSION (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
7 CHECK OUTPUT SIGNAL EMITTED FROM
TCM.
1) Return the engine to idling speed and move
select lever to “N” range.
2) Measure the voltage between TCM con-
nector and chassis ground.
Connector & terminal
(B54) No. 7 (+) — Chassis ground (
−):Is the voltage less than 0.5 V? Even if the
POWER indicator
light was blinking,
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
the harness or
connector in TCM
and transmission.Go to step 10.
8 CHECK OUTPUT SIGNAL EMITTED FROM
TCM USING SUBARU SELECT MONITOR.
1) Connect the connectors to TCM and trans-
mission.
2) Lift-up the vehicle and place rigid rack.
N
OTE:
Raise all wheels off ground.
3) Connect the 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).
N
OTE:
If ambient temperature is below 0°C (32°F),
drive the vehicle until ATF reaches its operating
temperature.
6) Read the data of lock-up duty solenoid
using Subaru Select Monitor.
 Lock-up duty solenoid is indicated in “%”.
7) Move the selector lever to “D” range and
slowly increase vehicle speed to 60 km/h (37
MPH). Wheels will lock-up.
N
OTE:
The speed difference between front and rear
wheels may light the ABS warning light, but this
indicates no malfunction. When AT control diag-
nosis is finished, perform the ABS memory
clearance procedure of on-board diagnostics
system. Mode.>Is the 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” range.
N
OTE:
The speed difference between front and rear
wheels may light the ABS warning light, but this
indicates no malfunction. When AT control diag-
nosis is finished, perform the ABS memory
clearance procedure of on-board diagnostics
system. Mode.>
2) Read the data of lock-up duty solenoid
using Subaru Select Monitor.Is the value 5%? Even if the
POWER indicator
light was blinking,
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
the harness or
connector in TCM
and transmission.Go to step 10. Step Check Yes No

4AT(H4SO)-79
AUTOMATIC TRANSMISSION (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
2 CHECK HARNESS CONNECTOR BETWEEN
TCM AND TRANSMISSION.
Measure the resistance harness connector
between TCM and chassis ground.
Connector & terminal
(B54) No. 6 — Chassis ground:Is the resistance more than 1
MΩ?Go to step 3.Repair the short
circuit in harness
between TCM and
transmission con-
nector.
3 CHECK TRANSFER DUTY SOLENOID.
Measure the resistance between transmission
connector and transmission terminals.
Connector & terminal
(T4) No. 6 — No. 16:Is the resistance 10 — 17 Ω? Go to step 4.Go to step 10.
4 PREPARE SUBARU SELECT MONITOR.Do you have a Subaru Select
Monitor?Go to step 7.Go to step 5.
5 CHECK OUTPUT SIGNAL EMITTED FROM
TCM.
1) Connect the connectors to TCM and trans-
mission.
2) Turn the ignition switch to ON (engine OFF).
3) Move the select lever to “P” range.
4) Throttle is fully closed.
5) Measure the voltage between TCM con-
nector and chassis ground.
Connector & terminal
(B54) No. 6 (+) — Chassis ground (
−):Is the voltage more than 8.5 V? Go to step 6.Go to step 9.
6 CHECK OUTPUT SIGNAL EMITTED FROM
TCM.
1) Move the select lever to “D” range.
2) Measure the voltage between TCM con-
nector and chassis ground.
Connector & terminal
(B54) No. 6 (+) — Chassis ground (
−):Is the voltage 3.0 — 6.0 V? Even if the
POWER indicator
light was blinking,
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
the harness or
connector in TCM
and transmission.Go to step 9.
7 CHECK OUTPUT SIGNAL EMITTED FROM
TCM USING SUBARU SELECT MONITOR.
1) Connect the connectors to TCM and trans-
mission.
2) Connect the Subaru Select Monitor to data
link connector.
3) Turn the ignition switch to ON (engine OFF)
and turn Subaru Select Monitor switch to ON.
4) Move the select lever to “D” range with throt-
tle fully open (vehicle speed 0 km/h (0 MPH)).
5) Read data of transfer duty solenoid using
Subaru Select Monitor.
 Transfer duty solenoid is indicated in “%”.Is the value 80 — 95%? Go to step 8.Go to step 9. Step Check Yes No

4AT(H4SO)-82
AUTOMATIC TRANSMISSION (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step Check Yes No
1 CHECK HARNESS CONNECTOR BETWEEN
TCM AND TRANSMISSION.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from TCM and
transmission.
3) Measure the resistance of harness
between TCM and transmission connector.
Connector & terminal
(B55) No. 24 — (B11) No. 19:Is the resistance less than 1
Ω?Go to step 2.Repair the open
circuit in harness
between TCM and
transmission con-
nector.
2 CHECK HARNESS CONNECTOR BETWEEN
TCM AND TRANSMISSION.
Measure the resistance of harness between
TCM and transmission connector.
Connector & terminal
(B54) No. 19 — (B11) No. 20:Is the resistance less than 1
Ω?Go to step 3.Repair the open cir-
cuit in harness
between TCM and
transmission, and
poor contact in cou-
pling connector.
3 CHECK HARNESS CONNECTOR BETWEEN
TCM AND TRANSMISSION.
Measure the resistance of harness between
TCM and chassis ground.
Connector & terminal
(B55) No. 24 — Chassis ground:Is the resistance more than 1
MΩ?Go to step 4.Repair the short
circuit in harness
between TCM and
transmission con-
nector.
4 CHECK HARNESS CONNECTOR BETWEEN
TCM AND TRANSMISSION.
Measure the resistance of harness between
TCM and chassis ground.
Connector & terminal
(B54) No. 19 — Chassis ground:Is the resistance more than 1
MΩ?Go to step 5.Repair the short
circuit in harness
between TCM and
transmission con-
nector.
5 CHECK REAR VEHICLE SPEED SENSOR.
Measure the resistance between transmission
connector receptacle’s terminals.
Connector & terminal
(T4) No. 19 — No. 20:Is the resistance 450 — 650
Ω?Go to step 6.Replace the rear
vehicle speed sen-
sor. 59, Rear Vehicle
Speed Sensor.>
6 PREPARE OSCILLOSCOPE.Do you have an oscilloscope? Go to step 10.Go to step 7.
7 PREPARE SUBARU SELECT MONITOR.Do you have a Subaru Select
Monitor?Go to step 9.Go to step 8.
8 CHECK INPUT SIGNAL FOR TCM.
1) Connect the connectors to TCM and trans-
mission.
2) Lift-up or raise the vehicle and place rigid
rack.
N
OTE:
Raise all wheels off floor.
3) Start the engine and set vehicle in 20 km/h
(12 MPH) condition.
N
OTE:
The speed difference between front and rear
wheels may light the ABS warning light, but this
indicates no malfunction. When AT control diag-
nosis is finished, perform the ABS memory
clearance procedure of on-board diagnostics
system. Mode.>
4) Measure the voltage between TCM con-
nector terminals.
Connector & terminal
(B55) No. 24 (+) — (B54) No. 19 (
−):Is the voltage more than AC 1
V?Even if the
POWER indicator
light was blinking,
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
the harness or
connector in TCM
and transmission.Go to step 11.

4AT(H4SO)-83
AUTOMATIC TRANSMISSION (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
9 CHECK INPUT SIGNAL FOR TCM USING
SUBARU SELECT MONITOR.
1) Connect the connectors to TCM and trans-
mission.
2) Connect the Subaru Select Monitor to data
link connector.
3) Lift-up or raise the vehicle and place rigid
rack.
N
OTE:
Raise all wheels off floor.
4) Turn the ignition switch to ON and turn Sub-
aru Select Monitor switch to ON.
5) Start the engine.
6) Read the data of vehicle speed using Sub-
aru Select Monitor.
 Compare the speedometer with Subaru
Select Monitor indications.
 Vehicle speed is indicated in “km/h” or
“MPH”.
7) Slowly increase the vehicle speed to 60 km/
h (37 MPH).
N
OTE:
The speed difference between front and rear
wheels may light the ABS warning light, but this
indicates no malfunction. When AT control diag-
nosis is finished, perform the ABS memory
clearance procedure of on-board diagnostics
system. Mode.>Does the speedometer indica-
tion increase as the Subaru
Select Monitor data increases?Even if the
POWER indicator
light was blinking,
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
the harness or
connector in TCM
and transmission.Go to step 11.
10 CHECK INPUT SIGNAL FOR TCM USING
OSCILLOSCOPE.
1) Connect the connectors to TCM and trans-
mission.
2) Lift-up or raise the vehicle and place rigid
rack.
NOTE:
Raise all wheels off floor.
3) Set the oscilloscope to TCM connector ter-
minals.
Connector & terminal
Positive probe; (B55) No. 24
Earth lead; (B54) No. 19
4) 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 diag-
nosis is finished, perform the ABS memory
clearance procedure of on-board diagnostics
system. Mode.>
5) Measure the signal voltage indicated on
oscilloscope.Is the signal voltage more than
AC 1 V?Even if the
POWER indicator
light was blinking,
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
the harness or
connector in TCM
and transmission.Go to step 11.
11 CHECK POOR CONTACT.Is there poor contact in rear
vehicle speed sensor circuit?Repair the poor
contact.Replace the TCM.
Transmission Con-
trol Module
(TCM).> Step Check Yes No

4AT(H4SO)-90
AUTOMATIC TRANSMISSION (DIAGNOSTIC)
Diagnostic Procedure without Diagnostic Trouble Code (DTC)
4 CHECK KICK-DOWN SWITCH.
Measure the resistance for kick-down switch
when releasing the accelerator pedal.
Te r m i n a l s
No. 1 — No. 2:Is the resistance more than 1
MΩ?Go to step 5.Replace the kick-
down switch. to SP(H4SO)-4,
Accelerator
Pedal.>
5 CHECK HARNESS CONNECTOR BETWEEN
TCM AND KICK-DOWN SWITCH.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from kick-down
switch.
3) Measure the resistance of harness connec-
tor between TCM and kick-down switch.
Connector & terminal
(B55) No. 11 — (B129) No. 2:Is the resistance less than 1
Ω?Go to step 6.Repair the open
circuit in harness
between TCM and
kick-down switch.
6 CHECK HARNESS CONNECTOR BETWEEN
TCM AND KICK-DOWN SWITCH.
Measure the resistance of harness connector
between TCM and chassis ground.
Connector & terminal
(B55) No. 11 — Chassis ground:Is the resistance more than 1
MΩ?Go to step 7.Repair the short
circuit in harness
between TCM and
chassis ground.
7 CHECK INPUT SIGNAL FOR TCM.
1) Turn the ignition switch to OFF.
2) Connect the connector to kick-down switch.
3) Turn the ignition switch to ON (engine OFF).
4) Measure the signal voltage for TCM when
depressing the accelerator pedal.
Connector & terminal
(B55) No. 11 (+) — Chassis ground (
−):Is the voltage less than 1 V? Go to step 8.Go to step 9.
8 CHECK INPUT SIGNAL FOR TCM.
Measure the signal voltage for TCM when
releasing the accelerator pedal.
Connector & terminal
(B55) No. 11 (+) — Chassis ground (
−):Is the voltage more than 6.5 V? A temporary poor
contact of the con-
nector and har-
ness may be the
cause. Repair the
harness and con-
nector in TCM.Go to step 9.
9 CHECK POOR CONTACT.Is there poor contact? Repair the poor
contact.Replace the TCM.
Transmission Con-
trol Module
(TCM).> Step Check Yes No

4AT(H4SO)-94
AUTOMATIC TRANSMISSION (DIAGNOSTIC)
Diagnostic Procedure without Diagnostic Trouble Code (DTC)
9 CHECK INPUT SIGNAL FOR TCM.
1) Connect the connectors to TCM and
POWER switch.
2) Turn the ignition switch to ON (engine OFF).
3) Measure the signal voltage for TCM while
turning POWER switch to OFF.
Connector & terminal
(B55) No. 23 (+) — Chassis ground (–):Is the voltage more than 10 V? Go to step 10.Replace the TCM.
Transmission Con-
trol Module
(TCM).>
10 CHECK INPUT SIGNAL FOR TCM.
Measure the signal voltage for TCM while turn-
ing POWER switch to ON.
Connector & terminal
(B55) No. 23 (+) — Chassis ground (–):Is the voltage less than 1 V? Go to step 11.Replace the TCM.
Transmission Con-
trol Module
(TCM).>
11 CHECK POOR CONTACT.Is there poor contact in
POWER switch circuit?Repair the poor
contact.A temporary poor
contact of the con-
nector or harness
or connector in
POWER switch cir-
cuit. Step Check Yes No