2004 SUBARU FORESTER check engine

EN(H4SO)-239
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step Check Yes No
1 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 connector and engine
ground.
Connector & terminal
(E7) No. 2 (+) — Engine ground (
−):
(E7) No. 5 (+) — Engine ground (
−):Is the voltage more than 10 V? Go to step 2.Repair harness
and connector.
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
2 CHECK HARNESS BETWEEN ECM AND
IDLE AIR CONTROL SOLENOID VALVE
CONNECTOR.
1) Turn the ignition switch to OFF.
2) Measure the resistance between ECM and
idle air control solenoid valve connector.
Connector & terminal
DTC P1510; (B134) No. 20 — (E7) No. 4:
DTC P1512; (B134) No. 6 — (E7) No. 1:
DTC P1514; (B134) No. 5 — (E7) No. 6:
DTC P1516; (B134) No. 19 — (E7) No. 3:Is the resistance less than 1
Ω?Go to step 3.Repair harness
and connector.
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
3 CHECK HARNESS BETWEEN ECM AND
IDLE AIR CONTROL SOLENOID VALVE
CONNECTOR.
1) Disconnect the connector from ECM.
2) Measure the resistance between ECM con-
nector and chassis ground.
Connector & terminal
DTC P1510; (B134) No. 20 — Chassis
ground:
DTC P1512; (B134) No. 6 — Chassis
ground:
DTC P1514; (B134) No. 5 — Chassis
ground:
DTC P1516; (B134) No. 19 — Chassis
ground:Is the resistance more than 1
MΩ?Go to step 4.Repair ground
short circuit in har-
ness between
ECM and idle air
control solenoid
valve connector.
4 CHECK POOR CONTACT.
Check poor contact in ECM connector and idle
air control solenoid valve connector.Is there poor contact in ECM
connector or idle air control
solenoid valve connector?Repair the poor
contact in ECM
connector or idle
air control solenoid
valve connector.Replace the idle
air control solenoid
valve. FU(H4SO)-33, Idle
Air Control Sole-
noid Valve.>

EN(H4SO)-241
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 DTC
using “List of Diag-
nostic Trouble
Code (DTC)”.
EN(H4SO)-72, List
of Diagnostic Trou-
ble Code (DTC).>Go to step 2.
2 CHECK GROUND CIRCUIT FOR ECM.
1) Turn the ignition switch to OFF.
2) Measure the resistance between ECM con-
nector and chassis ground.
Connector & terminal
(B134) No. 7 — Chassis ground:
(B135) No. 21 — Chassis ground:
(B137) No. 14 — Chassis ground:Is the resistance less than 5
Ω?Go to step 3.Repair harness
and connector.
N
OTE:
In this case repair
the following:
 Open circuit in
harness between
ECM connector
and engine ground
terminal
 Poor contact in
ECM connector.
 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 idle air con-
trol solenoid valve.
3) Turn the ignition switch to ON.
4) Measure the voltage between ECM con-
nector and chassis ground.
Connector & terminal
DTC P1511; (B134) No. 20 (+) — Chassis
ground (
−):
DTC P1513; (B134) No. 6 (+) — Chassis
ground (
−):
DTC P1515; (B134) No. 5 (+) — Chassis
ground (
−):
DTC P1517; (B134) No. 19 (+) — Chassis
ground (
−):Is the voltage more than 10 V? Repair battery
short circuit in har-
ness between
ECM and idle air
control solenoid
valve connector.
After repair,
replace the ECM.
FU(H4SO)-44,
Engine Control
Module (ECM).>Replace the ECM.
FU(H4SO)-44,
Engine Control
Module (ECM).>

EN(H4SO)-244
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step Check Yes No
1 CHECK OPERATION OF STARTER MOTOR.
 Place the inhibitor switch in the “P” or “N”
range. (AT model)
 Depress the clutch pedal. (MT model)Does the starter motor operate
when ignition switch to
START?Repair harness
and connector.
N
OTE:
In this case repair
the following:
 Open or ground
short circuit in har-
ness between
ECM and starter
motor connector.
 Poor contact in
ECM connector.Check starter
motor circuit. to EN(H4SO)-58,
STARTER
MOTOR CIR-
CUIT, Diagnostics
for Engine Start-
ing Failure.>

EN(H4SO)-246
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 OFF.
2) Measure the voltage between ECM and
chassis ground.
Connector & terminal
(B134) No. 9 (+) — Chassis ground (
−):Is the voltage more than 10 V? Repair the poor
contact in ECM
connector.Go to step 2.
2 CHECK HARNESS BETWEEN ECM AND
MAIN FUSE BOX CONNECTOR.
1) Disconnect the connector from ECM.
2) Measure the resistance of harness
between ECM and chassis ground.
Connector & terminal
(B135) No. 9 — Chassis ground:Is the resistance less than 10
Ω?Repair ground
short circuit in har-
ness between
ECM connector
and battery termi-
nal.Go to step 3.
3 CHECK FUSE SBF-5.Is the fuse blown out? Replace the fuse. Repair harness
and connector.
N
OTE:
In this case repair
the following:
 Open circuit in
harness between
ECM and battery
 Poor contact in
ECM connector.
 Poor contact in
battery terminal

EN(H4SO)-248
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step Check Yes No
1 CHECK OUTPUT SIGNAL FROM ECM.
1) Start the engine, and warm-up the engine.
2) Turn the ignition switch to OFF.
3) Turn the ignition switch to ON.
4) Measure the voltage between ECM and
chassis ground.
Connector & terminal
(B136) No. 15 (+) — Chassis ground (
−):Is the voltage more than 3 V? Repair the poor
contact in ECM
connector.Go to step 2.
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 ECM and chassis ground.
Connector & terminal
(B136) No. 15 — 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 HARNESS BETWEEN ECM AND
TCM CONNECTOR.
Measure the resistance of harness between
TCM and ECM connector.
Connector & terminal
(B136) No. 15 — (B55) No. 10:Is the resistance less than 1
Ω?Repair the poor
contact in ECM or
TCM connector.Repair the open
circuit in harness
between ECM and
TCM connector.

EN(H4SO)-250
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step Check Yes No
1 CHECK OUTPUT SIGNAL FROM ECM.
1) Start the engine, and warm-up the engine.
2) Turn the ignition switch to OFF.
3) Disconnect the connector from TCM.
4) Turn the ignition switch to ON.
5) Measure the voltage between ECM and
chassis ground.
Connector & terminal
(B136) No. 15 (+) — Chassis ground (
−):Is the voltage less than 3 V? Go to step 2.Repair battery
short circuit in har-
ness between
ECM and TCM
connector. After
repair, replace the
ECM. FU(H4SO)-44,
Engine Control
Module (ECM).>
2 CHECK HARNESS BETWEEN ECM AND
TCM CONNECTOR.
1) Turn the ignition switch to OFF.
2) Measure the voltage between ECM and
chassis ground.
Connector & terminal
(B136) No. 15 (+) — Chassis ground (
−):Is the voltage more than 10 V
by shaking the ECM harness
and connector?Repair the battery
short circuit in har-
ness between
ECM and TCM
connector. After
repair, replace the
ECM. FU(H4SO)-44,
Engine Control
Module (ECM).>Contact the SUB-
ARU dealer.
N
OTE:
Inspection by DTM
is required, because
probable cause is
deterioration of mul-
tiple parts.

EN(H4SO)-252
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) Measure the voltage between ECM and
chassis ground.
Connector & terminal
(B136) No. 1 (+) — Chassis ground (
−):Is the voltage more than 4.5 V? Go to step 2.Go to step 4.
2 CHECK INPUT SIGNAL FROM ECM.
Measure the voltage between ECM and chas-
sis ground.
Connector & terminal
(B136) No. 1 (+) — Chassis ground (
−):Is the voltage more than 10 V? Repair battery
short circuit in har-
ness between
ECM and TCM
connector.Go to step 3.
3 CHECK POOR CONTACT.
Check poor contact in ECM connector.Is there poor contact in ECM
connector?Repair the poor
contact in ECM
connector.Replace the ECM.
FU(H4SO)-44,
Engine Control
Module (ECM).>
4 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 and ECM connector.
Connector & terminal
(B136) No. 1 — (B56) No. 5:Is the resistance less than 1
Ω?Go to step 5.Repair the open
circuit in harness
between ECM and
TCM connector.
5 CHECK HARNESS BETWEEN ECM AND
TCM CONNECTOR.
Measure the resistance of harness between
ECM and chassis ground.
Connector & terminal
(B136) No. 1 — Chassis ground:Is the resistance more than 1
MΩ?Go to step 6.Repair ground
short circuit in har-
ness between
ECM and TCM
connector.
6 CHECK POOR CONTACT.
Check poor contact in TCM connector.Is there poor contact in TCM
connector?Repair poor con-
tact in TCM con-
nector.Replace the TCM.
Transmission Con-
trol Module
(TCM).>

EN(H4SO)-254
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) Measure the voltage between ECM and
chassis ground.
Connector & terminal
(B136) No. 18 (+) — Chassis ground (
−):Is the voltage more than 4.5 V? Go to step 2.Go to step 4.
2 CHECK INPUT SIGNAL FROM ECM.
Measure the voltage between ECM and chas-
sis ground.
Connector & terminal
(B136) No. 18 (+) — Chassis ground (
−):Is the voltage more than 10 V? Repair battery
short circuit in har-
ness between
ECM and TCM
connector.Go to step 3.
3 CHECK POOR CONTACT.
Check poor contact in ECM connector. Is there poor contact in ECM
connector?Repair the poor
contact in ECM
connector.Replace the ECM.
FU(H4SO)-44,
Engine Control
Module (ECM).>
4 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 and ECM connector.
Connector & terminal
(B136) No. 18 — (B56) No. 14:Is the resistance less than 1
Ω?Go to step 5.Repair the open
circuit in harness
between ECM and
TCM connector.
5 CHECK HARNESS BETWEEN ECM AND
TCM CONNECTOR.
Measure the resistance of harness between
ECM and chassis ground.
Connector & terminal
(B136) No. 18 — Chassis ground:Is the resistance more than 1
MΩ?Go to step 6.Repair ground
short circuit in har-
ness between
ECM and TCM
connector.
6 CHECK POOR CONTACT.
Check poor contact in TCM connector. Is there poor contact in TCM
connector?Repair poor con-
tact in TCM con-
nector.Replace the TCM.
Transmission Con-
trol Module
(TCM).>