2004 SUBARU FORESTER check engine

4AT(H4SO)-20
AUTOMATIC TRANSMISSION (DIAGNOSTIC)
Read Diagnostic Trouble Code (DTC)
7. Read Diagnostic Trouble Code (DTC)
A: OPERATION
1. WITHOUT SUBARU SELECT MONITOR
Step Check Yes No
1 PERFORM READ DTC.
1) Warm-up the engine.
2) Turn the ignition switch to OFF.
3) Turn the ignition switch to ON.
4) Start the engine.
5) Drive the vehicle at speeds greater than 20
km/h (12 MPH).
6) Stop the vehicle.
7) The brake pedal depressed and move
select lever to 1 range.
8) Turn the ignition switch to OFF.
9) Turn the ignition switch to ON.
10)Move the select lever “2” range.
11)Move the select lever “1” range.
12)Move the select lever “2” range.
13)Move the select lever “3” range.
14)Move the select lever “D” range.Does the POWER indicator
light blink at 4 Hz intervals?
NOTE: Blinks every 0.125 (1/8)
seconds (until the ignition
switch is turned OFF).Go to step 2.Repair the power
supply and ground
circuit. 4AT(H4SO)-30,
CHECK POWER
SUPPLY AND
GROUND LINE,
INSPECTION,
Power Indicator
Light Display.>
2 CHECK POWER INDICATOR LIGHT.Does the POWER indicator
light blink at 2 Hz intervals?
NOTE: Blinks every 0.25 (1/4)
seconds (until ignition switch is
turned to OFF).The AT system is
normal.Go to step 3.
3 CHECK POWER INDICATOR LIGHT.Is the DTC outputted by the
blink of POWER indicator
light?Inspect the prob-
lem correspond-
ing with DTC.
N
OTE:
Record all DTCs.Go to step 4.
4 CHECK POWER INDICATOR LIGHT.Does the POWER indicator
light remain illuminated?Repair the
POWER indicator
light circuit to 4AT(H4SO)-25,
INSPECTION,
Power Indicator
Light Display.>, or
Inspect inhibitor
switch, wiring,
TCM, etc.Calling up the DTC
again.

4AT(H4SO)-24
AUTOMATIC TRANSMISSION (DIAGNOSTIC)
Power Indicator Light Display
10.Power Indicator Light Display
A: OPERATION
When any on-board diagnostics item is malfunctioning, the display on POWER indicator light blinks from the
time malfunction is detected after starting the engine until ignition switch is turned to OFF. The malfunctioning
part or unit can be determined by a DTC during on-board diagnostics operation. Problems which occurred
previously can also be identified through the memory function. If the Power indicator does not show a prob-
lem (although a problem is occurring), the problem can be determined by checking the performance charac-
teristics of each sensor using select monitor. The indicator signal is as shown in the figure.
Perform the inspection when the POWER indicator light does not operate correctly. INSPECTION, Power Indicator Light Display.>
(A) Ignition switch (engine OFF) (C) Faulty (engine ON) (D) Normal (POWER switch ON)
(B) Normal (engine ON)
(1) ON (4) 0.25 sec. (6) POWER switch ON
(2) OFF (5) Blink (7) POWER switch OFF
(3) 2 sec.
AT-01109
(4)
(3)
(1)
(2)
(1)
(2)
(1)
(2)
(1)
(2)(3)
(3)(5)
(6) (A)
(B)
(C)
(D)
(7)

4AT(H4SO)-28
AUTOMATIC TRANSMISSION (DIAGNOSTIC)
Power Indicator Light Display
Step Check Yes No
1 CHECK POWER INDICATOR LIGHT.
Turn the ignition switch to ON (engine OFF).Does the POWER indicator
light illuminate?Go to step 3.Go to step 2.
2 CHECK POWER INDICATOR LIGHT.
1) Turn the ignition switch to OFF.
2) Remove the combination meter.
3) Remove the POWER indicator light bulb
from combination meter.Is the POWER indicator light
bulb OK?Go to step 4.Replace the
POWER indicator
light bulb.
3 CHECK POWER INDICATOR LIGHT.
Perform “Read Diagnostic Trouble Code
(DTC)”. nostic Trouble Code (DTC).>Does the POWER indicator
light blink?A temporary poor
contact of the con-
nector or harness
may be the cause.
Repair the har-
ness or connector
in TCM, inhibitor
switch and combi-
nation meter.Go to step 9.
4 CHECK FUSE (No. 14).
Remove the fuse (No. 14).Is the fuse (No. 14) blown out? Replace the fuse
(No. 14). If
replaced fuse (No.
14) is blown out
easily, repair short
circuit in harness
between fuse (No.
14) and combina-
tion meter.Go to step 5.
5 CHECK HARNESS CONNECTOR BETWEEN
COMBINATION METER AND IGNITION
SWITCH.
1) Turn the ignition switch to ON (engine
OFF).
2) Measure the voltage between combination
meter connector and chassis ground.
Connector & terminal
(i10) No. 9 (+) — Chassis ground (
−):Is the voltage more than 9 V? Go to step 6.Repair the open
circuit in harness
between combina-
tion meter and bat-
tery.
6 CHECK COMBINATION METER.
Measure the voltage between combination
meter connector and chassis ground.
Connector & terminal
(i11) No. 2 (+) — Chassis ground (
−):Is the voltage less than 9 V? Repair the combi-
nation meter.
Combination
Meter Assembly.>Go to step 7.
7 CHECK OPEN CIRCUIT OF HARNESS.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from combination
meter connector.
3) Measure the resistance of harness
between combination meter.
Connector & terminal
(B56) No. 11 — (i11) No. 2:Is the resistance less than 1
Ω?Go to step 8.Repair the open
circuit in harness
between TCM and
combination
meter, and poor
contact in cou-
pling connector.
8 CHECK INPUT SIGNAL FOR TCM.
1) Connect the connector to TCM and combi-
nation meter.
2) Turn the ignition switch to ON (engine
OFF).
3) Measure the voltage between TCM con-
nector and chassis ground.
Connector & terminal
(B56) No. 11 (+) — Chassis ground (
−):Is the voltage less than 1 V? Even if the
POWER indicator
lights up, the cir-
cuit has returned
to a normal condi-
tion at this time. A
temporary poor
contact of the con-
nector or harness
may be the cause.
Repair the har-
ness or connector
in TCM.Replace the TCM.
Transmission Con-
trol Module
(TCM).>

4AT(H4SO)-31
AUTOMATIC TRANSMISSION (DIAGNOSTIC)
Power Indicator Light Display
Step Check Yes No
1 CHECK BATTERY TERMINAL.
Turn the ignition switch to OFF.Is there poor contact at battery
terminal?Repair or tighten
the battery termi-
nal.Go to step 2.
2 CHECK POWER SUPPLY OF TCM.
1) Disconnect the connector from TCM.
2) Turn the ignition switch to ON.
3) Measure the voltage between TCM con-
nector and chassis ground.
Connector & terminal
(B56) No. 1 (+) — Chassis ground (
−):Is the voltage 10 — 13 V? Go to step 4.Go to step 3.
3 CHECK FUSE (NO. 4).
Remove the fuse (No. 4).Is the fuse (No. 4) blown out? Replace the fuse
(No. 4). If replaced
fuse (No. 4) has
blown out easily,
repair short circuit
in harness
between fuse (No.
4) and TCM.Repair the open
circuit in harness
between fuse (No.
4) and TCM, or
fuse (No. 4) and
battery, and poor
contact in cou-
pling connector.
4 CHECK IGNITION POWER SUPPLY CIR-
CUIT.
1) Turn the ignition switch to ON (engine
OFF).
2) Measure the ignition power supply voltage
between TCM connector and chassis ground.
Connector & terminal
(B54) No. 23 (+) — Chassis ground (–):
(B54) No. 24 (+) — Chassis ground (–):Is the voltage 10 — 13 V? Go to step 6.Go to step 5.
5 CHECK FUSE (NO. 11).
Remove the fuse (No. 11).Is the fuse (No. 11) blown out? Replace the fuse
(No. 11). If
replaced fuse (No.
11) has blown out
easily, repair short
circuit in harness
between fuse (No.
11) and TCM.Repair the open
circuit in harness
between fuse (No.
11) and TCM, or
fuse (No. 11) and
battery, and poor
contact in cou-
pling connector.
6 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
(B56) No. 19 — (B11) No. 16:
(B54) No. 21 — (B11) No. 16:Is the resistance less than 1
Ω?Go to step 7.Repair the open
circuit in harness
between TCM,
transmission har-
ness connector,
and poor contact
in coupling con-
nector.
7 CHECK HARNESS CONNECTOR BETWEEN
TRANSMISSION AND TRANSMISSION
GROUND.
Measure the resistance of harness between
transmission and transmission ground.
Connector & terminal
(T4) No. 16 — Transmission ground:Is the resistance less than 1
Ω?Go to step 8.Repair the open
circuit in harness
between transmis-
sion and transmis-
sion ground.
8 CHECK POOR CONTACT IN CONNECTORS.Is there poor contact in control
module power supply, ground
line and data link connector?Repair the con-
nector.Replace the TCM.
Transmission Con-
trol Module
(TCM).>

4AT(H4SO)-33
AUTOMATIC TRANSMISSION (DIAGNOSTIC)
Diagnostic Procedure for Subaru Select Monitor Communication
Step Check Yes No
1 CHECK SUBARU SELECT MONITOR POW-
ER SUPPLY CIRCUIT.
Measure the voltage between data link con-
nector and chassis ground.
Connector & terminal
(B40) No. 1 (+) — Chassis ground (
−):Is the voltage more than 10 V? Go to step 2.Repair the har-
ness and connec-
tor between battery
and data link con-
nector, and poor
contact in coupling
connector.
2 CHECK SUBARU SELECT MONITOR
GROUND CIRCUIT.
Measure the resistance of harness between
data link connector and chassis ground.
Connector & terminal
(B40) No. 12 — Chassis ground:
(B40) No. 13 — Chassis ground:Is the resistance less than 1
Ω?Go to step 3.Repair the open
circuit in harness
between data link
connector and
ground terminal,
and poor contact
in coupling con-
nector.
3 CHECK COMMUNICATION OF SELECT
MONITOR.
1) Turn the ignition switch to ON.
2) Using the Subaru Select Monitor, check
whether communication to engine systems can
be executed normally.Are the contents of engine sys-
tem displayed on Subaru
Select Monitor?Go to step 8.Go to step 4.
4 CHECK COMMUNICATION OF SELECT
MONITOR.
1) Turn the ignition switch to OFF.
2) Disconnect the TCM connector.
3) Check whether communication to engine
systems can be executed normally.Are the contents of engine sys-
tem displayed on Subaru
Select Monitor?Go to step 6.Go to step 5.
5 CHECK COMMUNICATION OF SELECT
MONITOR.
1) Turn the ignition switch to OFF.
2) Connect the TCM connector.
3) Disconnect the ECM connector.
4) Check whether communication to transmis-
sion systems can be executed normally.Are the contents of transmis-
sion displayed on Subaru
Select Monitor?Inspect the ECM. Go to step 6.
6 CHECK HARNESS CONNECTOR BETWEEN
EACH CONTROL MODULE AND DATA LINK
CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the TCM, ECM.
3) Measure the resistance between data link
connector and chassis ground.
Connector & terminal
(B40) No. 10 — Chassis ground:
(B40) No. 6 — Chassis ground:Is the resistance more than 1
MΩ?Go to step 7.Repair the har-
ness and connec-
tor between each
control module and
data link connector.
7 CHECK OUTPUT SIGNAL FOR TCM.
1) Turn the ignition switch to ON.
2) Measure the voltage between data link con-
nector and chassis ground.
Connector & terminal
(B40) No. 10 (+) — Chassis ground (
−):Is the voltage more than 1 V? Repair the har-
ness and connec-
tor between each
control module
and data link con-
nector.Go to step 8.
8 CHECK HARNESS/CONNECTOR BETWEEN
TCM AND DATA LINK CONNECTOR.
Measure the resistance between TCM connec-
tor and data link connector.
Connector & terminal
(B56) No. 15 — (B40) No. 10:Is the resistance less than 0.5
Ω?Go to step 9.Repair the harness
and connector
between TCM and
data link connector.

4AT(H4SO)-37
AUTOMATIC TRANSMISSION (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step Check Yes No
1 CHECK HARNESS CONNECTOR BETWEEN
TCM AND ECM.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from TCM and
ECM.
3) Measure the resistance of harness
between TCM and ECM connector.
Connector & terminal
(B55) No. 17 — (B134) No. 10:Is the resistance less than 1
Ω?Go to step 2.Repair the open
circuit in harness
between TCM and
ECM connector.
2 CHECK HARNESS CONNECTOR BETWEEN
TCM AND ECM.
Measure the resistance of harness between
TCM connector and chassis ground.
Connector & terminal
(B55) No. 17 — Chassis ground:Is the resistance more than 1
MΩ?Go to step 3.Repair the short
circuit in harness
between TCM and
ECM connector.
3 PREPARE SUBARU SELECT MONITOR.Do you have a Subaru Select
Monitor?Go to step 5.Go to step 4.
4 CHECK INPUT SIGNAL FOR TCM.
1) Connect the connectors to TCM and ECM.
2) Turn the ignition switch to ON (engine
OFF).
3) Measure the voltage between TCM con-
nector and chassis ground.
Connector & terminal
(B55) No. 17 (+) — Chassis ground (
−):Is the voltage more than 10.5
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 ECM.Go to step 6.
5 CHECK INPUT SIGNAL FOR TCM USING
SUBARU SELECT MONITOR.
1) Connect the connectors to TCM and ECM.
2) Connect the Subaru Select Monitor to data
link connector.
3) Start the engine and turn Subaru Select
Monitor switch to ON.
4) Warm-up the engine until engine coolant
temperature is above 80°C (176°F).
5) Idle the engine.
6) Read the data of engine speed using Sub-
aru Select Monitor.
 Display shows the engine speed signal value
sent from ECM.Is the revolution value same as
tachometer reading shown on
combination meter?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 ECM.Go to step 6.
6 CHECK POOR CONTACT.Is there poor contact in engine
speed signal circuit?Repair the poor
contact.Go to step 7.
7 CONFIRM DTC 11.Replace the ECM with a new
one. Does the DTC 11 appear
again, after memory has been
cleared?Replace the TCM.
Transmission Con-
trol Module
(TCM).>Replace the ECM.
FU(H4SO)-44,
Engine Control
Module (ECM).>

4AT(H4SO)-39
AUTOMATIC TRANSMISSION (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step Check Yes No
1 CHECK HARNESS CONNECTOR BETWEEN
TCM AND ATF TEMPERATURE SENSOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from transmis-
sion and TCM.
3) Measure the resistance of harness
between TCM and transmission connector.
Connector & terminal
(B54) No. 20 — (B11) No. 12: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 ATF TEMPERATURE SENSOR.
Measure the resistance of harness between
TCM and transmission connector.
Connector & terminal
(B54) No. 11 — (B11) No. 11: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 ATF TEMPERATURE SENSOR.
Measure the resistance of harness between
TCM connector and chassis ground.
Connector & terminal
(B54) No. 20 — 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 ATF TEMPERATURE SENSOR.
Measure the resistance of harness between
TCM connector and chassis ground.
Connector & terminal
(B54) No. 11 — 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 ATF TEMPERATURE SENSOR.
1) Turn the ignition switch to OFF.
2) Connect the connectors to transmission
and TCM.
3) Turn the ignition switch to ON and start
engine.
4) Warm-up the transmission until ATF tem-
perature reaches to 80°C (176°F).
NOTE:
If ambient temperature is below 0°C (32°F),
drive the vehicle until ATF reaches its operating
temperature.
5) Disconnect the connector from transmis-
sion.
6) Measure the resistance between transmis-
sion connector terminals.
Connector & terminal
(T4) No. 11 — No. 12:Is the resistance 275 — 375
Ω?Go to step 6.Replace the ATF
temperature sen-
sor. 71, Shift Sole-
noids, Duty Sole-
noids and ATF
Temperature Sen-
sor.>
6 CHECK ATF TEMPERATURE SENSOR.
1) Turn the ignition switch to ON (engine
OFF).
2) Measure the resistance between transmis-
sion connector terminals.
Connector & terminal
(T4) No. 11 — No. 12:Does the resistance value
increase while ATF tempera-
ture decreases? Go to step 7.Replace the ATF
temperature sen-
sor. 71, Shift Sole-
noids, Duty Sole-
noids and ATF
Temperature Sen-
sor.>
7 PREPARE SUBARU SELECT MONITOR.Do you have a Subaru Select
Monitor?Go to step 9.Go to step 8.

4AT(H4SO)-40
AUTOMATIC TRANSMISSION (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
8 CHECK INPUT SIGNAL FOR TCM.
1) Connect the connector to transmission.
2) Warm-up the transmission until ATF tem-
perature is about 80°C (176°F).
N
OTE:
If ambient temperature is below 0°C (32°F),
drive the vehicle until ATF reaches its operating
temperature.
3) Measure the voltage between TCM con-
nector terminal.
Connector & terminal
(B54) No. 11 (+) — No. 20 (
−):Is the voltage 0.4 — 0.9 V? Even if the
POWER indicator
light was blinking,
the circuit has
returned to a nor-
mal condition at
this time. Tempo-
rary poor contact
of the connector or
harness may be
the cause. Repair
the harness or
contact in ATF
temperature sen-
sor and transmis-
sion connector.Go to step 10.
9 CHECK INPUT SIGNAL FOR TCM USING
SUBARU SELECT MONITOR.
1) Connect the connector to transmission.
2) Turn the ignition switch to ON (engine OFF).Does the ATF temperature
gradually decrease?Even if the
POWER indicator
light was blinking,
the circuit has
returned to a nor-
mal condition at
this time. Tempo-
rary poor contact
of the connector or
harness may be
the cause. Repair
the harness or
contact in ATF
temperature sen-
sor and transmis-
sion connector.Go to step 10.
10 CHECK POOR CONTACT.Is there poor contact in ATF
temperature sensor circuit?Repair the poor
contact.Replace the TCM.
Transmission Con-
trol Module
(TCM).> Step Check Yes No