check engine SUBARU FORESTER 2004 Service Repair Manual

EN(H4DOTC)-201
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 the rele-
vant DTC using
“List of Diagnostic
Trouble Code
(DTC)”. EN(H4DOTC)-74,
List of Diagnostic
Trouble Code
(DTC).>Go to step 2.
2 CHECK FUEL LEVEL SENSOR.
1) Remove the fuel pump assembly. FU(H4DOTC)-62, Fuel Pump.>
2) While moving the fuel level sensor float up
and down, make sure that the resistance
between fuel level sensor terminals changes
smoothly.
Te r m i n a l s
No. 3 — No. 5:Does the resistance change
smoothly between approx. 0.5
— 52 Ω?Go to step 3.Replace the fuel
level sensor. to FU(H4DOTC)-
64, Fuel Level
Sensor.>
3 CHECK FUEL SUB LEVEL SENSOR.
1) Remove the fuel sub level sensor. FU(H4DOTC)-65, Fuel Sub Level Sensor.>
2) While moving the fuel sub level sensor float
up and down, make sure that the resistance
between fuel level sensor terminals changes
smoothly.
Te r m i n a l s
No. 1 — No. 2: Does the resistance change
smoothly between approx. 0.5
— 44 Ω?Repair poor con-
tact in ECM, com-
bination meter and
coupling connec-
tors.Replace the fuel
sub level sensor.
FU(H4DOTC)-65,
Fuel Sub Level
Sensor.>

EN(H4DOTC)-202
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
BD:DTC P0483 COOLING FAN RATIONALITY CHECK
DTC DETECTING CONDITION:
Two consecutive driving cycles with fault
TROUBLE SYMPTOM:
 Occurrence of noise
 Over-heating
CAUTION:
After repair or replacement of faulty parts, conduct Clear Memory Mode ERATION, Clear Memory Mode.> and Inspection Mode .
NOTE:
If the vehicle, with the engine idling, is placed very close to a wall or another vehicle, preventing normal cool-
ing function, the OBD system may detect malfunction.

EN(H4DOTC)-204
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 the rele-
vant DTC using
“List of Diagnostic
Trouble Code
(DTC)”. EN(H4DOTC)-74,
List of Diagnostic
Trouble Code
(DTC).>Check the radiator
fan, fan motor and
thermostat and
replace the ther-
mostat when it is
stuck. CO(H4SO)-35,
Radiator Main Fan
and Fan Motor.>
CO(H4SO)-40,
Radiator Sub Fan
and Fan Motor.>

EN(H4DOTC)-206
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step Check Yes No
1 CHECK TRANSMISSION TYPE.Is the transmission type AT? Go to step 2.Go to step 4.
2 CHECK HARNESS BETWEEN ECM AND
TCM CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM and
TCM.
3) Measure the resistance of harness
between TCM connector and chassis ground.
Connector & terminal
(B56) No. 1 — Chassis ground:Is the resistance more than 1
MΩ?Go to step 3.Repair ground
short circuit in har-
ness between
ECM and TCM
connector.
3 CHECK POOR CONTACT.
Check poor contact in TCM connector.Is there poor contact in TCM
connector?Repair poor con-
tact in TCM con-
nector.Contact the SUB-
ARU dealer.
4 CHECK HARNESS BETWEEN VEHICLE
SPEED SENSOR AND ECM CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from vehicle
speed sensor ECM.
3) Measure the resistance of harness
between vehicle speed sensor connector and
chassis ground.
Connector & terminal
(B17) No. 1 — Chassis ground:Is the resistance more than 1
MΩ?Go to step 5.Repair ground
short circuit in har-
ness between
vehicle speed sen-
sor and ECM con-
nector.
5 CHECK POOR CONTACT.
Check poor contact in vehicle speed sensor
connector.Is there poor contact in vehicle
speed sensor connector?Repair poor con-
tact in vehicle
speed sensor con-
nector.Replace the vehi-
cle speed sensor.
Vehicle Speed
Sensor.>

EN(H4DOTC)-208
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step Check Yes No
1 CHECK TRANSMISSION TYPE.Is the transmission type AT? Go to step 2.Go to step 3.
2 CHECK SPEEDOMETER OPERATION IN
COMBINATION METER.Does speedometer operate
normally?Go to step 3.Check the speed-
ometer. IDI-13, Speedom-
eter.>
3 CHECK HARNESS BETWEEN ECM AND
COMBINATION METER CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from the combi-
nation meter.
3) Measure the resistance between ECM and
combination meter connector.
Connector & terminal
(B134) No. 1 — (i11) No. 2:Is the resistance less than 10
Ω?Repair the poor
contact in ECM
connector.Repair the har-
ness and connec-
tor.
N
OTE:
In this case repair
the following:
 Open circuit in
harness between
ECM and combi-
nation meter con-
nector
 Poor contact in
ECM connector.
 Poor contact in
combination meter
connector
 Poor contact in
coupling connector

EN(H4DOTC)-210
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 the rele-
vant DTC using
“List of Diagnostic
Trouble Code
(DTC)”. EN(H4DOTC)-74,
List of Diagnostic
Trouble Code
(DTC).>
N
OTE:
In this case, it is
not necessary to
inspect DTC
P0506.Go to step 2.
2 CHECK IDLE AIR CONTROL SOLENOID
VALVE.
1) Turn the ignition switch to OFF.
2) Remove the idle air control solenoid valve
from the throttle body. 37, REMOVAL, Idle Air Control Solenoid
Va l ve. >
3) Using an air gun, force air into the idle air
control solenoid valve by-pass air inlet.Confirm
that forced air subsequently escapes from both
main air passage and assist air passage.Does air flow out? Go to step 3.Replace the idle
air control solenoid
valve. FU(H4DOTC)-37,
Idle Air Control
Solenoid Valve.>
After replace, Go
to step 3.
3 CHECK IDLE AIR CONTROL SOLENOID
VALVE DUTY RATIO.
1) Turn the ignition switch to ON.
2) Start the engine, and warm-up the engine.
3) Turn all accessory switches to OFF.
4) Read the data of idle air control solenoid
duty ratio using Subaru Select Monitor or
OBD-II general scan tool.
NOTE:
 Subaru Select Monitor
For detailed operation procedure, refer to
“READ CURRENT DATA SHOWN ON DIS-
PLAY FOR ENGINE”. 33, Subaru Select Monitor.>
 OBD-II general scan tool
For detailed operation procedures, refer to the
OBD-II General Scan Tool Operation Manual.Is the duty ratio more than 60% Go to step 4.END.
4 CHECK BY-PASS AIR LINE.
1) Turn the ignition switch to OFF.
2) Remove the idle air control solenoid valve
from the throttle body. 37, REMOVAL, Idle Air Control Solenoid
Va l ve. >
3) Remove the throttle body from the intake
manifold. REMOVAL, Throttle Body.>
4) Using an air gun, force air into the solenoid
valve installation area and throttle valve inte-
rior.Confirm that forced air subsequently
escapes from both these areas.Does air flow out? Replace the idle
air control solenoid
valve. FU(H4DOTC)-37,
Idle Air Control
Solenoid Valve.>Replace the throt-
tle body. FU(H4DOTC)-13,
Throttle Body.>

EN(H4DOTC)-212
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 the rele-
vant DTC using
“List of Diagnostic
Trouble Code
(DTC)”. EN(H4DOTC)-74,
List of Diagnostic
Trouble Code
(DTC).>
N
OTE:
In this case, it is
not necessary to
inspect DTC
P0507.Go to step 2.
2 CHECK THROTTLE CABLE.Does the throttle cable have
play for adjustment?Go to step 3.Adjust throttle
cable. SP(H4SO)-9,
INSTALLATION,
Accelerator Con-
trol Cable.>
3 CHECK AIR INTAKE SYSTEM.
1) Turn the ignition switch to ON.
2) Start and idle the engine.
3) Check the following items:
 Loose installation of intake manifold, idle air
control solenoid valve and throttle body
 Cracks of intake manifold gasket, idle air
control solenoid valve gasket and throttle body
gasket
 Disconnections of vacuum hosesIs there any fault in air intake
system?Repair air suction
and leaks.Replace the idle
air control solenoid
valve. FU(H4DOTC)-37,
Idle Air Control
Solenoid Valve.>

EN(H4DOTC)-214
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 and
chassis ground.
Connector & terminal
(B134) No. 27 (+) — Chassis ground (
−):Is the voltage more than 3 V? Repair the poor
contact in ECM
connector.Go to step 2.
2 CHECK POWER SUPPLY TO IDLE AIR CON-
TROL SOLENOID VALVE.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from idle air con-
trol solenoid valve.
3) Turn the ignition switch to ON.
4) Measure the voltage between idle air con-
trol solenoid valve and engine ground.
Connector & terminal
(E7) No. 2 (+) — Engine ground (
−):Is the voltage more than 10 V? Go to step 3.Repair the har-
ness and connec-
tor.
N
OTE:
In this case repair
the following:
 Open circuit in
harness between
idle air control
solenoid valve and
main relay connec-
tor
 Poor contact in
coupling connector
3 CHECK HARNESS BETWEEN ECM AND
IDLE AIR CONTROL SOLENOID VALVE
CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Measure the resistance of harness
between ECM and idle air control solenoid
valve connector.
Connector & terminal
(B134) No. 27 — (E7) No. 1:Is the resistance less than 1
Ω?Go to step 4.Repair the har-
ness and connec-
tor.
N
OTE:
In this case repair
the following:
 Open circuit in
harness between
ECM and idle air
control solenoid
valve connector
 Poor contact in
coupling connector
4 CHECK HARNESS BETWEEN ECM AND
IDLE AIR CONTROL SOLENOID VALVE
CONNECTOR.
Measure the resistance of harness between
ECM and chassis ground.
Connector & terminal
(B134) No. 10 — Chassis ground:Is the resistance more than 1
MΩ?Go to step 5.Repair ground
short circuit in har-
ness between
ECM and idle air
control solenoid
valve connector.
5 CHECK GROUND CIRCUIT OF IDLE AIR
CONTROL SOLENOID VALVE.
Measure the resistance of harness between
idle air control solenoid valve connector and
engine ground.
Connector & terminal
(E7) No. 3 — Engine ground:Is the resistance less than 5
Ω?Go to step 6.Repair open circuit
in harness
between idle air
control solenoid
valve connector
and engine ground
cable.
6 CHECK POOR CONTACT.
Check poor contact in ECM and idle air control
solenoid valve connectors. Is there poor contact in ECM
and idle air control solenoid
valve connectors?Repair poor con-
tact in ECM and
idle air control
solenoid valve
connectors.Replace the idle
air control solenoid
valve. FU(H4DOTC)-37,
Idle Air Control
Solenoid Valve.>

EN(H4DOTC)-216
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step Check Yes No
1 CHECK THROTTLE CABLE.Does the throttle cable have
play for adjustment?Go to step 2.Adjust throttle
cable. SP(H4SO)-9,
Accelerator Con-
trol Cable.>
2 CHECK OUTPUT SIGNAL FROM ECM.
1) Turn the ignition switch to ON.
2) Measure the voltage between ECM and
chassis ground.
Connector & terminal
(B134) No. 27 (+) — Chassis ground (
−):Is the voltage more than 10 V? Go to step 3.Go to step 4.
3 CHECK OUTPUT SIGNAL FROM ECM.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from idle air con-
trol solenoid valve.
3) Turn the ignition switch to ON.
4) Measure the voltage between ECM and
chassis ground.
Connector & terminal
(B134) No. 27 (+) — Chassis ground (
−):Is the voltage more than 10 V? Repair battery
short circuit in har-
ness between
ECM and idle air
control solenoid
valve connec-
tor.After repair,
replace the ECM.
FU(H4DOTC)-50,
Engine Control
Module (ECM).>Replace the idle
air control solenoid
valve and ECM.
FU(H4DOTC)-37,
Idle Air Control
Solenoid Valve.>
FU(H4DOTC)-50,
Engine Control
Module (ECM).>
4 CHECK OUTPUT SIGNAL FROM ECM.
Measure the voltage between ECM and chas-
sis ground.
Connector & terminal
(B134) No. 27 (+) — Chassis ground (
−):Does the voltage change by
shaking the harness and con-
nector of ECM while monitor-
ing the value with voltage
meter?Repair battery
short circuit in har-
ness between
ECM and idle air
control solenoid
valve connec-
tor.After repair,
replace the ECM.
FU(H4DOTC)-50,
Engine Control
Module (ECM).>Contact the SUB-
ARU dealer.
N
OTE:
Inspection by DTM
is required, be-
cause probable
cause is deteriora-
tion of multiple
parts.

EN(H4DOTC)-218
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step Check Yes No
1 CHECK OPERATION OF STARTER MOTOR.Does the starter motor operate
when ignition switch to ON?Repair battery
short circuit in
starter motor cir-
cuit.After repair,
replace the ECM.
FU(H4DOTC)-50,
Engine Control
Module (ECM).>Check starter
motor circuit. to EN(H4DOTC)-
60, STARTER
MOTOR CIR-
CUIT, Diagnostics
for Engine Start-
ing Failure.>