check engine light SUBARU FORESTER 2004 Service Repair Manual

EN(H4DOTC 2.5)-180
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step Check Yes No
1 CHECK INPUT SIGNAL FROM ECM.
1) Turn the ignition switch to ON.
2) Shift the select lever to other than “N” and
“P” ranges.
3) Measure the voltage between ECM and
chassis ground.
Connector & terminal
(B137) No. 9 (+) — Chassis ground (
−):Is the voltage 4.5 — 5.5 V? Even if the mal-
function indicator
light illuminates,
the circuit has
returned to a nor-
mal condition at
this time.Go to step 2.
2 CHECK HARNESS BETWEEN ECM AND
TRANSMISSION HARNESS CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from ECM and
transmission harness connector (T3).
3) Measure the resistance of harness
between ECM connector and chassis ground.
Connector & terminal
(B137) No. 9 — Chassis ground:Is the resistance more than 1
MΩ?Go to step 3.Repair ground
short circuit in har-
ness between
ECM and trans-
mission harness
connector.
3 CHECK TRANSMISSION HARNESS CON-
NECTOR.
1) Disconnect the connector from inhibitor switch.
2) Measure the resistance of harness
between transmission harness connector and
engine ground.
Connector & terminal
(T3) No. 12 — Engine ground:Is the resistance more than 1
MΩ?Go to step 4.Repair ground
short circuit in har-
ness between
transmission har-
ness and inhibitor
switch connector.
4 CHECK INHIBITOR SWITCH.
Measure the resistance between inhibitor
switch connector the receptacle’s terminals in
selector lever except for “N” range.
Te r m i n a l s
No. 7 — No. 12:Is the resistance more than 1
MΩ?Go to step 5.Replace the inhibi-
tor switch. 4AT-51, Inhibitor
Switch.>
5 CHECK SELECTOR CABLE CONNECTION.Is there any fault in selector cable
connection to inhibitor switch?Repair selector
cable connection.
INSPECTION,
Select Cable.>Contact the SUB-
ARU dealer.
N
OTE:
Inspection by DTM
is required, be-
cause probable
cause is deteriora-
tion of multiple
parts.

EN(H4DOTC 2.5)-189
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step Check Yes No
1 CHECK CURRENT DATA.
1) Start the engine.
2) Read the data of throttle position sensor
signal using Subaru Select Monitor or OBD-II
general scan tool.
N
OTE:
 Subaru Select Monitor
For detailed operation procedure, refer to
“READ CURRENT DATA SHOWN ON DIS-
PLAY FOR ENGINE”. 2.5)-27, Subaru Select Monitor.>
 OBD-II general scan tool
For detailed operation procedures, refer to the
OBD-II General Scan Tool Operation Manual.Is the voltage less than 0.1 V? Go to step 2.Even if the mal-
function indicator
light illuminates,
the circuit has
returned to a nor-
mal condition at
this time. A tempo-
rary poor contact
of the connector
may be the cause.
N
OTE:
In this case repair
the following:
 Poor contact in
throttle position
sensor connector
 Poor contact in
ECM connector.
 Poor contact in
coupling connector
2 CHECK INPUT SIGNAL FROM ECM.
Measure the voltage between ECM connector
and chassis ground while tumble generator
valve is fully closed.
Connector & terminal
(B136) No. 16 (+) — Chassis ground (
−):Is the voltage more than 4.5 V? Go to step 4.Go to step 3.
3 CHECK INPUT SIGNAL FROM ECM.
Measure the voltage between ECM connector
and chassis ground.
Connector & terminal
(B136) No. 16 (+) — Chassis ground (
−):Does the voltage change by
shaking the harness and con-
nector of ECM while monitoring
the value with voltage meter?Repair the poor
contact in ECM
connector.Contact the SUB-
ARU dealer.
N
OTE:
Inspection by DTM
is required, because
probable cause is
deterioration of mul-
tiple parts.
4 CHECK INPUT SIGNAL FROM ECM.
Measure the voltage between ECM connector
and chassis ground.
Connector & terminal
(B136) No. 26 (+) — Chassis ground (
−):Is the voltage less than 0.1 V? Go to step 6.Go to step 5.
5 CHECK INPUT SIGNAL FOR ECM WITH
SUBARU SELECT MONITOR.
Measure the voltage between ECM connector
and chassis ground.Does the voltage change by
shaking the harness and con-
nector of ECM while monitoring
the value with Subaru Select
Monitor?Repair the poor
contact in ECM
connector.Go to step 6.

EN(H4DOTC 2.5)-192
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step Check Yes No
1 CHECK CURRENT DATA.
1) Start the engine.
2) Read the data of throttle position sensor
signal using Subaru Select Monitor or OBD-II
general scan tool.
N
OTE:
 Subaru Select Monitor
For detailed operation procedure, refer to
“READ CURRENT DATA SHOWN ON DIS-
PLAY FOR ENGINE”. 2.5)-27, Subaru Select Monitor.>
 OBD-II general scan tool
For detailed operation procedures, refer to the
OBD-II General Scan Tool Operation Manual.Is the voltage more than 4.9 V? Go to step 2.Even if the mal-
function indicator
light illuminates,
the circuit has
returned to a nor-
mal condition at
this time. A tempo-
rary poor contact
of the connector
may be the cause.
N
OTE:
In this case repair
the following:
 Poor contact in
tumble generator
valve position sen-
sor connector
 Poor contact in
ECM connector.
 Poor contact in
coupling connector
2 CHECK HARNESS BETWEEN TUMBLE
GENERATOR VALVE POSITION SENSOR
AND ECM CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from throttle
position sensor.
3) Measure the resistance of harness
between throttle position sensor connector and
engine ground.
Connector & terminal
(E50) No. 2 — Engine ground:Is the resistance less than 5
Ω?Go to step 3.Repair the harness
and connector.
N
OTE:
In this case repair
the following:
 Open circuit in
harness between
tumble generator
valve position sen-
sor and ECM con-
nector
 Poor contact in
coupling connector
 Poor contact in
joint connector
3 CHECK HARNESS BETWEEN THROTTLE
POSITION SENSOR AND ECM CONNEC-
TOR.
1) Turn the ignition switch to ON.
2) Measure the voltage between throttle posi-
tion sensor connector and engine ground.
Connector & terminal
(E50) No. 3 (+) — Engine ground (
−):Is the voltage more than 4.9 V? Repair battery
short circuit in har-
ness between tum-
ble generator valve
position sensor
and ECM connec-
tor. After repair,
replace the ECM.
FU(H4DOTC 2.5)-
41, Engine Con-
trol Module
(ECM).>Replace the tum-
ble generator valve
assembly. FU(H4DOTC 2.5)-
33, Tumble Gener-
ator Valve Assem-
bly.>

EN(H4DOTC 2.5)-194
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step Check Yes No
1 CHECK CURRENT DATA.
1) Start the engine.
2) Read the data of tumble generator valve
position sensor signal using Subaru Select
Monitor or OBD-II general scan tool.
N
OTE:
 Subaru Select Monitor
For detailed operation procedure, refer to
“READ CURRENT DATA SHOWN ON DIS-
PLAY FOR ENGINE”. 2.5)-27, Subaru Select Monitor.>
 OBD-II general scan tool
For detailed operation procedures, refer to the
OBD-II General Scan Tool Operation Manual.Is the voltage less than 0.1 V? Go to step 2.Even if the mal-
function indicator
light illuminates,
the circuit has
returned to a nor-
mal condition at
this time. A tempo-
rary poor contact
of the connector
may be the cause.
N
OTE:
In this case repair
the following:
 Poor contact in
tumble generator
valve position sen-
sor connector
 Poor contact in
ECM connector.
 Poor contact in
coupling connector
2 CHECK INPUT SIGNAL FROM ECM.
Measure the voltage between ECM connector
and chassis ground while throttle valve is fully
closed.
Connector & terminal
(B136) No. 16 (+) — Chassis ground (
−):Is the voltage more than 4.5 V? Go to step 4.Go to step 3.
3 CHECK INPUT SIGNAL FROM ECM.
Measure the voltage between ECM connector
and chassis ground.
Connector & terminal
(B136) No. 16 (+) — Chassis ground (
−):Does the voltage change by
shaking the harness and con-
nector of ECM while monitoring
the value with voltage meter?Repair the poor
contact in ECM
connector.Contact the SUB-
ARU dealer.
N
OTE:
Inspection by DTM
is required, because
probable cause is
deterioration of mul-
tiple parts.
4 CHECK INPUT SIGNAL FROM ECM.
Measure the voltage between ECM connector
and chassis ground.
Connector & terminal
(B136) No. 27 (+) — Chassis ground (
−):Is the voltage less than 0.1 V? Go to step 6.Go to step 5.
5 CHECK INPUT SIGNAL FOR ECM WITH
SUBARU SELECT MONITOR.
Measure the voltage between ECM connector
and chassis ground.Does the voltage change by
shaking the harness and con-
nector of ECM while monitoring
the value with Subaru Select
Monitor?Repair the poor
contact in ECM
connector.Go to step 6.

EN(H4DOTC 2.5)-197
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step Check Yes No
1 CHECK CURRENT DATA.
1) Start the engine.
2) Read the data of tumble generator valve
position sensor signal using Subaru Select
Monitor or OBD-II general scan tool.
N
OTE:
 Subaru Select Monitor
For detailed operation procedure, refer to “READ
CURRENT DATA SHOWN ON DISPLAY FOR
ENGINE”. aru Select Monitor.>
 OBD-II general scan tool
For detailed operation procedures, refer to the
OBD-II General Scan Tool Operation Manual.Is the voltage more than 4.9 V? Go to step 2.Even if the mal-
function indicator
light illuminates,
the circuit has
returned to a nor-
mal condition at
this time. A tempo-
rary poor contact
of the connector
may be the cause.
N
OTE:
In this case repair
the following:
 Poor contact in
tumble generator
valve position sen-
sor connector
 Poor contact in
ECM connector.
 Poor contact in
coupling connector
2 CHECK HARNESS BETWEEN TUMBLE
GENERATOR VALVE POSITION SENSOR
AND ECM CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from throttle
position sensor.
3) Measure the resistance of harness
between tumble generator valve position sen-
sor connector and engine ground.
Connector & terminal
(E54) No. 2 — Engine ground:Is the resistance less than 5
Ω?Go to step 3.Repair the harness
and connector.
N
OTE:
In this case repair
the following:
 Open circuit in
harness between
tumble generator
valve position sen-
sor and ECM con-
nector
 Poor contact in
coupling connector
 Poor contact in
joint connector
3 CHECK HARNESS BETWEEN TUMBLE
GENERATOR VALVE POSITION SENSOR
AND ECM CONNECTOR.
1) Turn the ignition switch to ON.
2) Measure the voltage between throttle posi-
tion sensor connector and engine ground.
Connector & terminal
(E54) No. 3 (+) — Engine ground (
−):Is the voltage more than 4.9 V? Repair battery
short circuit in har-
ness between tum-
ble generator valve
position sensor
and ECM connec-
tor. After repair,
replace the ECM.
FU(H4DOTC 2.5)-
41, Engine Con-
trol Module
(ECM).>Replace the tum-
ble generator valve
assembly. FU(H4DOTC 2.5)-
33, Tumble Gener-
ator Valve Assem-
bly.>

4AT-32
AUTOMATIC TRANSMISSION
Road Test
4. Road Test
A: INSPECTION
1. GENERAL PRECAUTION
Road tests should be conducted to properly diag-
nose the condition of the automatic transmission.
NOTE:
When performing the test, do not exceed posted
speed limit.
2. D RANGE SHIFT FUNCTION
Check shifting between 1st ←→ 2nd ←→ 3rd ←→
4th while driving on normal city streets.
3. D RANGE SHIFT SHOCK
Check the shock level when shifting up during nor-
mal driving.
4. KICK-DOWN FUNCTION
Check kick-down for each gear. Also check the
kick-down shock level.
5. ENGINE BRAKE OPERATION
 Check the 3rd gear engine brake when shifting
down from D ←→ 3rd range while driving in 4th
gear of D range [50 — 60 km/h (31 — 37 MPH)].
 Check the 2nd gear engine brake when shifting
between 3rd ←→ 2nd range while driving in the 3rd
range of 3rd gear [40 — 50 km/h (25 — 31 MPH)].
 Check the 1st gear engine brake when shifting
between 2nd ←→ 1st range while driving in the 2nd
range of 2nd gear [20 — 30 km/h (12 — 19 MPH)].
6. LOCK-UP FUNCTION
 Check that rpm does not change sharply when
the axle pedal is lightly depressed when driving on
flat roads at 60 km/h (37 MPH).
 Check slip lock-up with following procedure.
Subaru Select Monitor is needed for checking (EC,
EK model).
Before start checking, check that the DTC is not ex-
isted using Subaru Select Monitor. When the DTC
is existed, perform the collective action with DTC
and check that the DTC is not existed again, and
then start the checking.
1) The check performed on flat and straight road or
free roller.
NOTE:
 Slip lock-up does not operate when the vehicle is
lifted up, because of not occurring surface resis-
tance.
 Also checking on the free roller, check with de-
pressing foot brake lightly to make the checking
easier, because the surface resistance will be defi-
cient2) Connect the Subaru Select Monitor.
3) Check ATF temperature using Subaru Select
Monitor.
NOTE:
 ATF temperature is between 50 — 100°C (122
— 212°F).
 When the temperature is low, warm-up the ATF
by running the vehicle or etc.
4) Start the engine, and make the lock-up duty be
able to read on data display of Subaru Select Mon-
itor.
5) 35 — 40 Drive the vehicle at a constant speed of
35 — 40 km/h (22 — 25 MPH).
6) Read the lock-up duty while vehicle is running.
Standard value:
25 — 45%
NOTE:
On the free roller, the value sometimes lowers.
 Slip lock-up control is not operating when the
lock-up duty is less than 5%, or when the lock-up
duty goes down immediately after starts rise. On
these cases, improper ATF or deterioration of ATF
may be the cause. Check the amount of ATF or re-
place them, and then recheck it.
7. P RANGE OPERATION
Stop the vehicle on an uphill grade of 5% or more
and shift to “P” range. Check that the vehicle does
not move when the parking brake is released.
8. NOISE AND VIBRATION
Check for unusual sounds and vibration while driv-
ing and during shifting.
9. CLIMBING CONTROL FUNCTION
 Check that the gear remains in 3rd when going
up a grade.
 Check that the gear remains in 3rd when apply-
ing the brakes while going down a grade.
10.TRANSFER CLUTCH
Check tight corner braking when the vehicle started
with steering fully turned.
11.OIL LEAKS
After the driving test, inspect for oil leaks.

4AT-70
AUTOMATIC TRANSMISSION
Air Bleeding of Control Valve
18.Air Bleeding of Control Valve
A: PROCEDURE
1) Lift-up the vehicle with shifting the select lever to
“P” range and applying the parking brake.
2) Connect the Subaru Select Monitor to the vehi-
cle.
3) Make sure there is no trouble code using Subaru
Select Monitor.
4) Using Subaru Select Monitor, check that the
ATF temperature is in less than 60°C (140°F).
nostic Procedure.>
5) Power OFF the Subaru Select Monitor.
6) Turn the ignition switch to “OFF”.
7) Shift the select lever to “R” range.
8) Depress the brake pedal fully until the air bleed-
ing is completed.
9) Turn the ignition switch to ON.
10) Shift the select lever to “P” range, and then wait
for more than 3 seconds.
11) Shift the select lever to “R” range, and then wait
for more than 3 seconds.
12) Shift the select lever to “N” range, and then wait
for more than 3 seconds.
13) Shift the select lever to “D” range, and then wait
for more than 3 seconds.
14) Shift the select lever to “N” range, and then wait
for more than 3 seconds.
15) Slightly depress the accelerator pedal fully.
16) Slightly release the accelerator pedal fully.
17) Start the engine.
18) Shift the select lever to “D” range.
19) Turn the Subaru Select Monitor switch to ON.
20) Select {Each System Check} in «Main Menu»
of Subaru Select Monitor.
21) On the «System Selection Menu» display
screen, select the “Transmission”. Air bleeding of
control valve starts on transmission. At this time,
the POWER indicator light in combination meter
blinks at 2 Hz. When the POWER indicator light
does not blink, repeat the procedures from step 4).
22) Air bleeding of control valve is finished when
blinking of POWER indicator light in combination
meter changes from 2 Hz to 0.5 Hz.
NOTE:
When blinking of POWER indicator light changes
from 2 Hz to 4 Hz during air bleeding, repeat the
procedure from step 4).
23) Shift the select lever to “N” range, and then turn
the ignition switch to OFF.
24) Shift the select lever to the “P” range, and then
finish the air bleeding.

4AT(H4SO)-6
AUTOMATIC TRANSMISSION (DIAGNOSTIC)
General Description
5. OPERATION OF SHIFT SELECT LEVER
Make sure there is no abnormal noise, dragging or
contact pattern in each select lever range.
WARNING:
Stop the engine while checking operation of se-
lect lever.
6. POWER SWITCH
Make sure that the POWER indicator light in com-
bination meter comes ON, when turning the POW-
ER switch to ON.
7. HOLD SWITCH
Make sure that the HOLD indicator light in combi-
nation meter comes ON, when turning the HOLD
switch to ON.
AT-00413
P
R
N
D
3
2
1
AT-00319
AT-00320

4AT(H4SO)-13
AUTOMATIC TRANSMISSION (DIAGNOSTIC)
Transmission Control Module (TCM) I/O Signal
Inhibitor
switch“2” range
switchB55 6Select lever in “2” range Less than 1
—
Select lever in any other
than “2” rangeMore than 8
“1” range
switchB55 7Select lever in “1” range Less than 1
—
Select lever in any other
than “1” rangeMore than 8
Brake switch B55 12Brake pedal depressed More than 10.5
—
Brake pedal released Less than 1
Kick-down switch B55 11Throttle fully opened Less than 1
—
Throttle fully closed More than 6.5
AT OIL TEMP warning light B56 10Light ON Less than 1
—
Light OFF More than 9
Throttle position sensor B54 3Throttle fully closed 0.2 — 1.0
—
Throttle fully open 4.2 — 4.7
Throttle position sensor
power supplyB54 2Ignition switch ON (with
engine OFF)4.8 — 5.3 —
ATF temperature sensor B54 11ATF temperature 20°C
(68°F)1.6 — 2.0 2.1 k — 2.9 k
ATF temperature 80°C
(176°F)0.4 — 0.9 275 — 375
Rear vehicle speed sensor B55 24Vehicle stopped 0
450 — 650
Vehicle speed at least 20
km/h (12 MPH)More than 1 (AC range)
Front vehicle speed sensor B55 18Vehicle stopped 0
450 — 650
Vehicle speed at least 20
km/h (12 MPH)More than 1 (AC range)
Torque converter turbine
speed sensorB55 8Engine idling after warm-
up (D range)0
450 — 650
Engine idling after warm-
up (N range)More than 1 (AC range)
Vehicle speed output signal B56 17Vehicle speed at most 10
km/h (6 MPH)Less than 1 ←
→ More than 4—
Engine speed signal B55 17Ignition switch ON (with
engine OFF)More than 10.5
—
Ignition switch ON (with
engine ON)8 — 11
Cruise set signal B55 22When cruise control is set
(SET lamp ON)Less than 1
—
When cruise control is not
set (SET lamp OFF)More than 6.5
Torque control signal 1 B56 5Ignition switch ON (with
engine ON)More than 4 —
Torque control signal 2 B56 14Ignition switch ON (with
engine ON)More than 4 —
Torque control cut signal B55 10Ignition switch ON
(After engine is warmed-up)8—
Intake manifold pressure
signalB54 1 Engine idling after warm-up 0.4 — 1.6 —
Shift solenoid 1 B54 221st or 4th gear More than 9
10 — 16
2nd or 3rd gear Less than 1
Shift solenoid 2 B54 51st or 2nd gear More than 9
10 — 16
3rd or 4th gear Less than 1 Check with ignition switch ON.
ContentConnector
No.Terminal No. Measuring conditions Voltage (V)Resistance
to chassis
ground (Ω)

4AT(H4SO)-14
AUTOMATIC TRANSMISSION (DIAGNOSTIC)
Transmission Control Module (TCM) I/O Signal
Line pressure duty solenoid B54 9Ignition switch ON (with
engine OFF)
Throttle fully closed after
war m-up1.5 — 4.0
2.0 — 4.5
Ignition switch ON (with
engine OFF)
Throttle fully open after
war m-upLess than 0.5
Lock-up duty solenoid B54 7When lock up occurs More than 8.5
10 — 17
When lock up is released Less than 0.5
Transfer duty solenoid B54 6Fuse on FWD switch Less than 0.5
10 — 17 Fuse removed from FWD
switch (with throttle fully
open and with select lever
in 1st gear)More than 8.5
2-4 brake duty solenoid B54 18Throttle fully closed (with
engine OFF) after warm-up1.5 — 5.0
2.0 — 4.5
Throttle fully open (with
engine OFF) after warm-upLess than 0.5
2-4 brake timing solenoid B54 161st gear Less than 1
10 — 16
3rd gear More than 9
Low clutch timing solenoid B54 152nd gear Less than 1
10 — 16
4th gear More than 9
HOLD switch B55 16HOLD switch ON Less than 1 —
HOLD switch OFF More than 8 —
POWER switch B55 23POWER switch ON Less than 1 —
POWER switch OFF More than 10 —
POWER indicator light B56 11Light ON Less than 1 —
Light OFF More than 9 —
FWD switch B55 20Fuse removed 6 — 9.1 —
Fuse installed Less than 1 —
FWD indicator light B56 2Fused on FWD switch Less than 1 —
Fuse removed from FWD
switchMore than 9 —
ABS signal B55 21ABS switch ON Less than 1 —
ABS switch OFF 6.5 — 15 —
Sensor ground line 1 B54 20 — 0 Less than 1
Sensor ground line 2 B55 9 — 0 Less than 1
System ground lineB56 19
— 0 Less than 1
B54 21
Sensor ground line 3 B54 10 — 0 Less than 1
Sensor ground line 4 B54 19 — 0 Less than 1
AT diagnosis signal B56 21 Ignition switch ONLess than 1 ←
→ More than 4—
Data link signal (Subaru
Select Monitor)B56 15 — — —Check with ignition switch ON.
ContentConnector
No.Terminal No. Measuring conditions Voltage (V)Resistance
to chassis
ground (Ω)