2004 SUBARU FORESTER turn signal

EN(H4SO)-50
ENGINE (DIAGNOSTIC)
Malfunction Indicator Light
Step Check Yes No
1 CHECK OUTPUT SIGNAL FROM ECM.
1) Turn the ignition switch to ON.
2) Measure the voltage between ECM con-
nector and chassis ground.
Connector & terminal
(B134) No. 28 (+) — Chassis ground (
−):Is the voltage less than 1 V? Go to step 4.Go to step 2.
2 CHECK POOR CONTACT.
Check for poor connection when shaking or
pulling ECM connector and harness.Does malfunction indicator
light illuminate?Repair the poor
contact in ECM
connector.Go to step 3.
3 CHECK ECM CONNECTOR.
Check the connection of ECM connector.Is the ECM connector correctly
connected?Replace the ECM.
FU(H4SO)-44,
Engine Control
Module (ECM).>Repair the con-
nection of ECM
connector.
4 CHECK HARNESS BETWEEN COMBINA-
TION METER AND ECM CONNECTOR.
1) Turn the ignition switch to OFF.
2) Remove the combination meter. IDI-10, Combination Meter Assembly.>
3) Disconnect the connector from ECM and
combination meter.
4) Measure the resistance of harness
between ECM and combination meter connec-
tor.
Connector & terminal
(B134) No. 28 — (i12) No. 1:Is the resistance less than 1
Ω?Go to step 5.Repair harness
and connector.
N
OTE:
In this case repair
the following:
 Open circuit in
harness between
ECM and combi-
nation meter con-
nector
 Poor contact in
coupling connector
5 CHECK POOR CONTACT.
Check poor contact in combination meter con-
nector.Is there poor contact in combi-
nation meter connector?Repair poor con-
tact in combination
meter connector.Go to step 6.

EN(H4SO)-59
ENGINE (DIAGNOSTIC)
Diagnostics for Engine Starting Failure
Step Check Yes No
1 CHECK BATTERY.
Check the battery voltage.Is the voltage more than 12 V? Go to step 2.Charge or replace
the battery.
2 CHECK INPUT SIGNAL FOR STARTER MO-
TOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from starter
motor.
3) Turn the ignition switch to START.
4) Measure the power supply voltage between
starter motor connector terminal and engine
ground.
Connector & terminal
(B14) No. 1 (+) — Engine ground (
−):
N
OTE:
 For AT model, shift the select lever to “P” or
“N” range.
 For MT model, depress the clutch pedal.Is the voltage more than 10 V? Go to step 3.Go to step 4.
3 CHECK GROUND CIRCUIT OF STARTER
MOTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the ground cable terminal from
starter motor.
3) Measure the resistance of ground cable
between ground cable terminal and engine
ground.Is the resistance less than 5
Ω?Check the starter
motor. SC(H4SO)-6,
Starter.>Repair open circuit
of ground cable.
4 CHECK HARNESS BETWEEN BATTERY
AND IGNITION SWITCH CONNECTOR.
1) Disconnect the connector from ignition
switch.
2) Measure the power supply voltage between
ignition switch connector and chassis ground.
Connector & terminal
(B72) No. 1 (+) — Chassis ground (
−):Is the voltage more than 10 V? Go to step 5.Repair open circuit
in harness
between ignition
switch and bat-
tery, and check
fuse SBF No. 4
and SBF No. 1.
5 CHECK IGNITION SWITCH.
1) Disconnect the connector from ignition
switch.
2) Measure the resistance between ignition
switch terminals while turning the ignition
switch to START position.
Te r m i n a l s
No. 1 — No. 3:Is the resistance less than 5
Ω?Go to step 6.Replace the igni-
tion switch.
6 CHECK TRANSMISSION TYPE.Is the transmission type AT? Go to step 7.Temporary poor
contact occurs.
Check poor con-
tact in each con-
nectors.
7 CHECK INHIBITOR SWITCH INPUT VOLT-
AGE.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from inhibitor
switch.
3) Connect the connector to ignition switch.
4) Measure the input voltage between inhibitor
switch connector terminal and engine ground
while turning the ignition switch to START posi-
tion.
Connector & terminal
(B12) No. 12 (+) — Engine ground (
−):Is the voltage more than 10 V? Go to step 8.Repair open or
ground short cir-
cuit in harness
between inhibitor
switch and ignition
switch.
N
OTE:
Check security sys-
tem (if equipped).

EN(H4SO)-65
ENGINE (DIAGNOSTIC)
Diagnostics for Engine Starting Failure
Step Check Yes No
1 CHECK IGNITION SYSTEM FOR SPARKS.
1) Remove the plug cord cap from each spark
plug.
2) Install the new spark plug on plug cord cap.
CAUTION:
Do not remove the spark plug from engine.
3) Contact the spark plug’s thread portion on
engine.
4) While opening the throttle valve fully, crank
the engine to check that spark occurs at each
cylinder.Does spark occur at each cyl-
inder?Check fuel pump
system. EN(H4SO)-67,
FUEL PUMP CIR-
CUIT, Diagnostics
for Engine Start-
ing Failure.>Go to step 2.
2 CHECK POWER SUPPLY CIRCUIT FOR IG-
NITION COIL & IGNITOR ASSY.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ignition coil
& ignitor ASSY.
3) Turn the ignition switch to ON.
4) Measure the power supply voltage between
ignition coil & ignitor ASSY connector and
engine ground.
Connector & terminal
(E12) No. 2 (+) — Engine ground (
−):Is the voltage more than 10 V? Go to step 3.Repair harness
and connector.
N
OTE:
In this case repair
the following:
 Open circuit in
harness between
ignition coil & igni-
tor ASSY, and
main relay connec-
tor
 Poor contact in
coupling connector
 Blown out fuse
3 CHECK HARNESS OF IGNITION COIL & IG-
NITOR ASSY GROUND CIRCUIT.
1) Turn the ignition switch to OFF.
2) Measure the resistance between ignition
coil & ignitor ASSY connector and engine
ground.
Connector & terminal
(E12) No. 3 — Engine ground:Is the resistance less than 5
Ω?Go to step 4.Repair harness
and connector.
N
OTE:
In this case repair
the following:
 Open circuit in
harness between
ignition coil & igni-
tor ASSY connec-
tor and engine
ground terminal
4 CHECK IGNITION COIL & IGNITOR ASSY.
1) Remove the spark plug cords.
2) Measure the resistance between spark
plug cord contact portions to check secondary
coil.
Te r m i n a l s
No. 1 — No. 2:
No. 3 — No. 4:Is the resistance 10 — 15 kΩ? Go to step 5.Replace the igni-
tion coil & ignitor
ASSY. IG(H4SO)-8, Igni-
tion Coil & Ignitor
Assembly.>
5 CHECK INPUT SIGNAL FOR IGNITION COIL
& IGNITOR ASSY.
1) Connect the connector to ignition coil &
ignitor ASSY.
2) Check if voltage varies synchronously with
engine speed when cranking, while monitoring
voltage between ignition coil & ignitor ASSY
connector and engine ground.
Connector & terminal
(E12) No. 1 (+) — Engine ground (
−):
(E12) No. 4 (+) — Engine ground (
−):Does the voltage vary more
than 10 V?Go to step 6.Replace the igni-
tion coil & ignitor
ASSY. IG(H4SO)-8, Igni-
tion Coil & Ignitor
Assembly.>

EN(H4SO)-81
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step Check Yes No
1 CHECK ANY OTHER DTC ON DISPLAY.Does the Subaru Select Moni-
tor or OBD-II general scan tool
indicate DTC P0031 and
P0037 at the same time?Go to step 2.Go to step 5.
2 CHECK POWER SUPPLY TO FRONT OXY-
GEN (A/F) SENSOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from front oxygen
(A/F) sensor.
3) Turn the ignition switch to ON.
4) Measure the voltage between front oxygen
(A/F) sensor connector and engine ground.
Connector & terminal
(B18) No. 4 (+) — Engine ground (
−):Is the voltage more than 10 V? Go to step 3.Repair the power
supply line.
N
OTE:
In this case repair
the following:
 Open circuit in
harness between
main relay and
front oxygen (A/F)
sensor connector
 Poor contact in
front oxygen (A/F)
sensor connector
 Poor contact in
main relay connec-
tor
3 CHECK GROUND CIRCUIT FOR ECM.
Measure the resistance of harness between
ECM connector and chassis ground.
Connector & terminal
(B136) No. 5 — Chassis ground:
(B136) No. 16 — Chassis ground:Is the resistance less than 5
Ω?Go to step 4.Repair harness
and connector.
N
OTE:
In this case repair
the following:
 Open circuit in
harness between
ECM and engine
ground terminal
 Poor contact in
ECM connector.
 Poor contact in
coupling connector
4 CHECK CURRENT DATA.
1) Start the engine.
2) Read the data of front oxygen (A/F) sensor
heater current using Subaru Select Monitor or
OBD-II general scan tool.
N
OTE:
 Subaru Select Monitor
For detailed operation procedure, refer to the
“READ CURRENT DATA FOR ENGINE”. to EN(H4SO)-29, Subaru Select Monitor.>
 OBD-II general scan tool
For detailed operation procedures, refer to the
OBD-II General Scan Tool Operation Manual.Is the current more than 0.2 A? Repair poor con-
tact connector.
N
OTE:
In this case repair
the following:
 Poor contact in
front oxygen (A/F)
sensor connector
 Poor contact in
ECM connector.Go to step 5.
5 CHECK INPUT SIGNAL FROM ECM.
1) Start and idle the engine.
2) Measure the voltage between ECM con-
nector and chassis ground.
Connector & terminal
(B136) No. 6 (+) — Chassis ground (
−):
(B136) No. 17 (+) — Chassis ground (
−):Is the voltage less than 1 V? Go to step 7.Go to step 6.
6 CHECK OUTPUT SIGNAL FROM ECM.
Measure the voltage between ECM connector
and chassis ground.
Connector & terminal
(B136) No. 6 (+) — Chassis ground (
−):
(B136) No. 17 (+) — Chassis ground (
−):Is the voltage less than 1 V by
shaking the ECM harness and
connector while monitoring the
value of voltage meter?Repair the poor
contact in ECM
connector.Go to step 7.

EN(H4SO)-84
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step Check Yes No
1 CHECK OUTPUT SIGNAL FROM ECM.
1) Turn the ignition switch to ON.
2) Measure the voltage between ECM con-
nector and chassis ground.
Connector & terminal
(B136) No. 6 (+) — Chassis ground (
−):
(B136) No. 17 (+) — Chassis ground (
−):Is the voltage more than 8 V? Go to step 2.Go to step 3.
2 CHECK FRONT OXYGEN (A/F) SENSOR
HEATER CURRENT.
1) Turn the ignition switch to OFF.
2) Repair battery short circuit in harness
between ECM and front oxygen (A/F) sensor
connector.
3) Turn the ignition switch to ON.
4) Read the data of front oxygen (A/F) sensor
heater current using Subaru Select Monitor or
OBD-II general scan tool.
N
OTE:
 Subaru Select Monitor
For detailed operation procedure, refer to the
“READ CURRENT DATA FOR ENGINE”. to EN(H4SO)-29, Subaru Select Monitor.>
 OBD-II general scan tool
For detailed operation procedures, refer to the
OBD-II General Scan Tool Operation Manual.Is the current more than 2.3 A? Replace the ECM.
FU(H4SO)-44,
Engine Control
Module (ECM).>END.
3 CHECK OUTPUT SIGNAL FROM ECM.
Measure the voltage between ECM connector
and chassis ground.
Connector & terminal
(B136) No. 6 (+) — Chassis ground (
−):
(B136) No. 17 (+) — Chassis ground (
−):Is the voltage more than 8 V by
shaking the ECM harness and
connector?Repair battery
short circuit in har-
ness between
ECM and front
oxygen (A/F) sen-
sor connector.END.

EN(H4SO)-86
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step Check Yes No
1 CHECK GROUND CIRCUIT FOR ECM.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Measure the resistance of harness
between ECM connector and chassis ground.
Connector & terminal
(B136) No. 16 — Chassis ground:
(B136) No. 5 — Chassis ground:Is the resistance less than 5
Ω?Go to step 2.Repair harness
and connector.
N
OTE:
In this case repair
the following:
 Open circuit in
harness between
ECM and engine
ground terminal
 Poor contact in
ECM connector.
 Poor contact in
coupling connector
2 CHECK CURRENT DATA.
1) Start the engine.
2) Read the data of rear oxygen (A/F) sensor
heater current using Subaru Select Monitor or
OBD-II general scan tool.
N
OTE:
 Subaru Select Monitor
For detailed operation procedure, refer to the
“READ CURRENT DATA FOR ENGINE”. to EN(H4SO)-29, Subaru Select Monitor.>
 OBD-II general scan tool
For detailed operation procedures, refer to the
OBD-II General Scan Tool Operation Manual.Is the current more than 0.2 A? Repair the con-
nector.
N
OTE:
In this case repair
the following:
 Poor contact in
rear oxygen sen-
sor connector
 Poor contact in
rear oxygen sen-
sor connecting
harness connector
 Poor contact in
ECM connector.Go to step 3.
3 CHECK OUTPUT SIGNAL FROM ECM.
1) Start and idle the engine.
2) Measure the voltage between ECM con-
nector and chassis ground.
Connector & terminal
(B136) No. 4 (+) — Chassis ground (
−):Is the voltage less than 1 V? Go to step 6.Go to step 4.
4 CHECK OUTPUT SIGNAL FROM ECM.
Measure the voltage between ECM connector
and chassis ground.
Connector & terminal
(B136) No. 4 (+) — Chassis ground (
−):Does the voltage change
within the range of 1 V by
shaking the ECM harness and
connector while monitoring the
value of voltage meter?Repair the poor
contact in ECM
connector.Go to step 5.
5 CHECK OUTPUT SIGNAL FROM ECM.
1) Disconnect the connector from rear oxygen
sensor.
2) Measure the voltage between ECM con-
nector and chassis ground.
Connector & terminal
(B136) No. 4 (+) — Chassis ground (
−):Is the voltage less than 1 V? Replace the ECM.
FU(H4SO)-44,
Engine Control
Module (ECM).>Repair battery
short circuit in har-
ness between
ECM and rear oxy-
gen sensor con-
nector. After
repair, replace the
ECM. FU(H4SO)-44,
Engine Control
Module (ECM).>

EN(H4SO)-89
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step Check Yes No
1 CHECK INPUT SIGNAL FROM ECM.
Measure the voltage between ECM connector
and chassis ground.
Connector & terminal
(B136) No. 4 (+) — Chassis ground (
−):Is the voltage more than 8 V? Go to step 2.Go to step 3.
2 CHECK CURRENT DATA.
1) Turn the ignition switch to OFF.
2) Repair battery short circuit in harness
between ECM and rear oxygen sensor con-
nector.
3) Turn the ignition switch to ON.
4) Read the data of rear oxygen (A/F) sensor
heater current using Subaru Select Monitor or
OBD-II general scan tool.
N
OTE:
 Subaru Select Monitor
For detailed operation procedure, refer to the
“READ CURRENT DATA FOR ENGINE”. to EN(H4SO)-29, Subaru Select Monitor.>
 OBD-II general scan tool
For detailed operation procedures, refer to the
OBD-II General Scan Tool Operation Manual.Is the current more than 7 A? Replace the ECM.
FU(H4SO)-44,
Engine Control
Module (ECM).>END.
3 CHECK POOR CONTACT.
Check poor contact in ECM connector. Is there poor contact in ECM
connector?Repair the poor
contact in ECM
connector.END.

EN(H4SO)-91
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step Check Yes No
1 CHECK ANY OTHER DTC ON DISPLAY.Is any other DTC displayed? Inspect DTC using
“List of Diagnostic
Trouble Code
(DTC)”. EN(H4SO)-72, List
of Diagnostic Trou-
ble Code (DTC).>Go to step 2.
2 CHECK AIR INTAKE SYSTEM.Are there holes, loose bolts or
disconnection of hose on air
intake system?Repair air intake
system.Go to step 3.
3 CHECK PRESSURE SENSOR.
1) Start and warm-up the engine until engine
coolant temperature is greater than 60°C
(140°F).
2) Shift the select lever in the “P” or “N” range.
3) Turn the A/C switch to OFF.
4) Turn all accessory switches to OFF.
5) Read the data of manifold absolute pres-
sure sensor signal using Subaru Select Moni-
tor or OBD-II general scan tool.
N
OTE:
 Subaru Select Monitor
For detailed operation procedure, refer to the
“READ CURRENT DATA FOR ENGINE”. to EN(H4SO)-29, Subaru Select Monitor.>
 OBD-II general scan tool
For detailed operation procedures, refer to the
OBD-II General Scan Tool Operation Manual.Is the measured value at Igni-
tion ON: 73.3 — 106.6 kPa
(550 — 800 mmHg, 21.65 —
31.50 inHg) Idling: 20.0 — 46.7
kPa (150 — 310 mmHg, 5.91
— 12.20 inHg)?Go to step 4.Replace the mani-
fold absolute pres-
sure sensor. to FU(H4SO)-31,
Manifold Absolute
Pressure Sensor.>
4 CHECK THROTTLE POSITION.
Read the data of throttle position signal using
Subaru Select Monitor or OBD-II general scan
tool.
NOTE:
 Subaru Select Monitor
For detailed operation procedure, refer to the
“READ CURRENT DATA FOR ENGINE”. to EN(H4SO)-29, Subaru Select Monitor.>
 OBD-II general scan tool
For detailed operation procedures, refer to the
OBD-II General Scan Tool Operation Manual.Is the value less than 5% when
the throttle fully closed?Go to step 5.Adjust or replace
the throttle posi-
tion sensor. to FU(H4SO)-29,
Throttle Position
Sensor.>
5 CHECK THROTTLE POSITION.Is the value more than 85%
when the throttle fully opens?Replace the mani-
fold absolute pres-
sure sensor. to FU(H4SO)-31,
Manifold Absolute
Pressure Sensor.>Replace the throt-
tle position sen-
sor. FU(H4SO)-29,
Throttle Position
Sensor.>