2004 SUBARU FORESTER check engine

EN(H4DOTC 2.5)-156
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 2.5)-
41, Engine Con-
trol Module
(ECM).>Check starter motor
circuit. EN(H4DOTC 2.5)-
55, STARTER
MOTOR CIR-
CUIT, Diagnostics
for Engine Starting
Failure.>

EN(H4DOTC 2.5)-159
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 2.5)-
65, List of Diag-
nostic Trouble
Code (DTC).>
N
OTE:
In this case, it is
not necessary to
inspect DTC
P0519.Go to step 2.
2 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 and
throttle body
 Cracks of intake manifold gasket and throttle
body gasket
 Disconnections of vacuum hosesIs there any fault in air intake
system?Repair air suction
and leaks.Go to step 3.
3 CHECK ELECTRONIC THROTTLE CON-
TROL.
1) Turn the ignition switch to OFF.
2) Replace the electronic throttle control.
3) Check the electronic throttle control.Are foreign matters found
inside the electronic throttle
control?Remove foreign
matters from the
electronic throttle
control.Perform the diag-
nosis of DTC
P2101.

EN(H4DOTC 2.5)-161
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 exhaust temperature sen-
sor 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 temperature more than
1,200°C (2,192°F)?Go to step 2.Repair the poor
contact.
N
OTE:
In this case repair
the following:
 Poor contact of
exhaust tempera-
ture sensor
 Poor contact in
ECM
 Poor contact in
joint connector
2 CHECK HARNESS BETWEEN EXHAUST
TEMPERATURE SENSOR AND ECM CON-
NECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from exhaust
temperature sensor.
3) Turn the ignition switch to ON.
4) Read the data of exhaust temperature sen-
sor 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 temperature less than
372°C (702°F)?Replace the
exhaust tempera-
ture sensor. to FU(H4DOTC
2.5)-40, Exhaust
Temperature Sen-
sor.>Repair ground
short circuit in har-
ness between
exhaust tempera-
ture sensor and
ECM connector.

EN(H4DOTC 2.5)-163
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 exhaust temperature sen-
sor 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 temperature less than
372°C (702°F)?Go to step 2.Repair the poor
contact.
N
OTE:
In this case repair
the following:
 Poor contact of
exhaust tempera-
ture sensor
 Poor contact in
ECM
 Poor contact in
joint connector
2 CHECK HARNESS BETWEEN EXHAUST
TEMPERATURE SENSOR AND ECM CON-
NECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from exhaust
temperature sensor.
3) Measure the voltage between exhaust tem-
perature sensor connector and engine ground.
Connector & terminal
(B279) No. 1 (+) — Engine ground (
−):Is the voltage more than 10 V? Repair battery
short circuit in har-
ness between
ECM and exhaust
temperature sen-
sor connector.Go to step 3.
3 CHECK HARNESS BETWEEN EXHAUST
TEMPERATURE SENSOR AND ECM CON-
NECTOR.
1) Turn the ignition switch to ON.
2) Measure the voltage between exhaust tem-
perature sensor connector and engine ground.
Connector & terminal
(B279) No. 1 (+) — Engine ground (
−):Is the voltage more than 10 V? Repair battery
short circuit in har-
ness between
ECM and exhaust
temperature sen-
sor connector.Go to step 4.
4 CHECK HARNESS BETWEEN EXHAUST
TEMPERATURE SENSOR AND ECM CON-
NECTOR.
Measure the voltage between exhaust temper-
ature sensor connector and engine ground.
Connector & terminal
(B279) No. 1 (+) — Engine ground (
−):Is the voltage more than 4 V? Go to step 5.Repair the harness
and connector.
N
OTE:
In this case repair
the following:
 Open circuit in
harness between
ECM and exhaust
temperature sen-
sor connector
 Poor contact of
exhaust tempera-
ture sensor con-
nector
 Poor contact in
ECM connector.
 Poor contact in
joint connector

EN(H4DOTC 2.5)-164
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
5 CHECK HARNESS BETWEEN EXHAUST
TEMPERATURE SENSOR AND ECM CON-
NECTOR.
1) Turn the ignition switch to OFF.
2) Measure the resistance of harness
between exhaust temperature sensor connec-
tor and engine ground.
Connector & terminal
(B279) No. 2 — Engine ground:Is the resistance less than 5
Ω?Replace the
exhaust tempera-
ture sensor. to FU(H4DOTC
2.5)-40, Exhaust
Temperature Sen-
sor.>Repair the harness
and connector.
N
OTE:
In this case repair
the following:
 Open circuit in
harness between
ECM and exhaust
temperature sen-
sor connector
 Poor contact of
exhaust tempera-
ture sensor con-
nector
 Poor contact in
ECM connector.
 Poor contact in
joint connector Step Check Yes No

EN(H4DOTC 2.5)-166
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step Check Yes No
1 CHECK HARNESS BETWEEN ECM AND
TCM.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Disconnect the connectors from TCM.
4) Measure the resistance between ECM and
TCM connectors.
Connector & terminal
(B137) No. 18 — (B55) No. 3:
(B137) No. 26 — (B55) No. 12:Is the resistance less than 1
Ω?Go to step 2.Repair the harness
and connector.
2 CHECK HARNESS BETWEEN ECM AND
TCM.
Measure the resistance between ECM connec-
tor and chassis ground.
Connector & terminal
(B137) No. 18 — Chassis ground:
(B137) No. 26 — Chassis ground:Is the resistance more than 1
MΩ?Go to step 3.Repair the harness
and connector.
3 CHECK HARNESS BETWEEN ECM AND
TCM.
Check the resistance between ECM connec-
tors.
Connector & terminal
(B137) No. 18 — (B137) No. 26:Is the resistance more than 1
MΩ?Go to step 4.Repair the harness
and connector.
4 CHECK AT SYSTEM CONDITION.
Perform the diagnosis for AT using Subaru
Select Monitor.Is DTC P1718 displayed? Check AT system. Replace the ECM.

EN(H4DOTC 2.5)-168
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
WIRING DIAGRAM:
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 P0604?Replace the ECM.
FU(H4DOTC 2.5)-
41, Engine Con-
trol Module
(ECM).>Temporary poor
contact occurs.
EN-02356
B72
B135
3412
BATTERY MAIN RELAY
SBF-4 SBF-1SBF-5
B72
D16 D7
B12
A6
A7
B1
B4
D1
D2
A34B5
B6
B19
D14
No.11
B47
E2 B21 1 2 3 5 6 4
ECM
E
E
1 4
B134
B135
B137 A:
B:
D:
14133
15
16
34 12
56123
4
56
78
91011 12
1314 15 16
B134 B21 B47B137 A: D:
B: IGNITION
SWITCH
56 7
82 1
94 310
24 22 23 25 11 12 13 14 15
26 27
2816 17
18 19 20 21
33 34 29
32 30 31
567
82 1
94 310
24 22 23 2511 12 13 14 15
26 27
2816 17 18 19
20 21
29 30 31 32 33 34 35
567
82 1
94 310
22 23 11 12 13 14 15
24 25
2616 17
18 19 20 21
27 28 29 30 31

EN(H4DOTC 2.5)-172
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
AT:DTC P0638 THROTTLE ACTUATOR CONTROL RANGE/PERFORMANCE
(BANK 1)
NOTE:
For diagnostic procedure, refer to DTC P2101. TUATOR CONTROL MOTOR CIRCUIT RANGE/PERFORMANCE, Diagnostic Procedure with Diagnostic
Trouble Code (DTC).>
Step Check Yes No
1 CHECK INPUT VOLTAGE OF ECM.
1) Turn the ignition switch to ON.
2) Measure the voltage between ECM con-
nector and ground.
Connector & terminal
(B135) No. 5 (+) — Chassis ground (
−):
(B135) No. 6 (+) — Chassis ground (
−):Is the voltage 10 — 13 V? Go to step 2.Repair open or
ground short cir-
cuit of power sup-
ply circuit.
2 CHECK INPUT VOLTAGE OF ECM.
1) Start the engine.
2) Measure the voltage between ECM con-
nector and ground.
Connector & terminal
(B135) No. 5 (+) — Chassis ground (
−):
(B135) No. 6 (+) — Chassis ground (
−):Is the voltage 13 — 15 V? Go to step 3.Repair open or
ground short cir-
cuit of power sup-
ply circuit.
3 CHECK ECM GROUND HARNESS.
Measure the voltage between ECM connector
and ground.
Connector & terminal
(B137) No. 1 (+) — Chassis ground (
−):
(B137) No. 2 (+) — Chassis ground (
−):Is the voltage less than 1 V? Repair the poor
contact in ECM
connector.
Replace the ECM
if defective.Further tighten the
engine ground ter-
minal.