SUBARU FORESTER 2004 Service Repair Manual

EN(H4SO)-223
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step Check Yes No
1 CHECK HARNESS BETWEEN ECM AND
TCM CONNECTOR.
1) Turn the ignition switch to ON.
2) Measure the voltage between ECM and
chassis ground.
Connector & terminal
(B134) No. 10 (+) — Chassis ground (
−):Is the voltage less than 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.
N
OTE:
In this case repair
the following:
 Poor contact in
ECM connector.
 Poor contact in
TCM connector
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
(B134) No. 10 — 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 OUTPUT SIGNAL FROM ECM.
1) Connect the connector to ECM.
2) Turn the ignition switch to ON.
3) Measure the voltage between ECM and
chassis ground.
Connector & terminal
(B134) No. 10 (+) — Chassis ground (
−):Is the voltage more than 5 V? Go to step 4.Repair the poor
contact in ECM
connector.
4 CHECK DTC FOR AUTOMATIC TRANSMIS-
SION.
Read DTC for automatic transmission. 4AT(H4SO)-20, Read Diagnostic Trouble Code
(DTC).>Does the DTC appear for auto-
matic transmission?Check the DTC for
automatic trans-
mission. 4AT(H4SO)-36,
Diagnostic Proce-
dure with Diagnos-
tic Trouble Code
(DTC).>Replace the TCM.
Transmission Con-
trol Module
(TCM).>

EN(H4SO)-224
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
BQ:DTC P0866 TCM COMMUNICATION CIRCUIT HIGH
DTC DETECTING CONDITION:
Two consecutive driving cycles with fault
CAUTION:
After repair or replacement of faulty parts, conduct Clear Memory Mode ERATION, Clear Memory Mode.> and Inspection Mode tion Mode.>.
WIRING DIAGRAM:
EN-00283
B134
10
ECM
B55TCM
17
B55
B134
1234567891011121314151617181920212223242526272829303132333435
123410 11 12
19 20 21135614 1578916 17 18
22 23 24

EN(H4SO)-225
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step Check Yes No
1 CHECK HARNESS BETWEEN ECM AND
TCM CONNECTOR.
1) Turn the ignition switch to ON.
2) Measure the voltage between ECM and
chassis ground.
Connector & terminal
(B134) No. 10 (+) — Chassis ground (
−):Is the voltage more than 10 V? Repair battery
short circuit in har-
ness between
ECM and TCM
connector.Go to step 2.
2 CHECK HARNESS BETWEEN ECM AND
TCM CONNECTOR.
Measure the voltage between ECM connector
and chassis ground.
Connector & terminal
(B134) No. 10 (+) — Chassis ground (
−):Is the voltage more than 4 V? Go to step 5.Go to step 3.
3 CHECK HARNESS BETWEEN ECM AND
TCM CONNECTOR.
Measure the voltage between ECM connector
and chassis ground.
Connector & terminal
(B134) No. 10 (+) — Chassis ground (
−):Is the voltage less than 1 V? Repair the poor
contact in ECM
connector.Go to step 4.
4 CHECK OUTPUT SIGNAL FROM ECM.
Measure the voltage between ECM and chas-
sis ground.
Connector & terminal
(B134) No. 10 (+) — Chassis ground (
−):Is the voltage 1 — 4 V? Even if the mal-
function indicator
light illuminates,
the circuit has
returned to a nor-
mal condition at
this time.
N
OTE:
In this case repair
the following:
 Poor contact in
ECM connector.
 Poor contact in
TCM connectorContact the SUB-
ARU dealer.
NOTE:
Inspection by DTM
is required, because
probable cause is
deterioration of mul-
tiple parts.
5 CHECK HARNESS BETWEEN ECM AND
TCM CONNECTOR.
Measure the voltage between TCM and chas-
sis ground.
Connector & terminal
(B55) No. 17 (+) — Chassis ground (
−):Is the voltage more than 4 V? Go to step 6.Repair the open
circuit in harness
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.Check TCM power
supply line and
grounding line.

EN(H4SO)-226
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
BR:DTC P1110 ATMOSPHERIC PRESSURE SENSOR CIRCUIT MALFUNCTION
(LOW INPUT)
DTC DETECTING CONDITION:
Immediately at fault recognition
TROUBLE SYMPTOM:
CAUTION:
After repair or replacement of faulty parts, conduct Clear Memory Mode ERATION, Clear Memory Mode.> and Inspection Mode tion Mode.>.
BS:DTC P1111 ATMOSPHERIC PRESSURE SENSOR CIRCUIT MALFUNCTION
(HIGH INPUT)
DTC DETECTING CONDITION:
Immediately at fault recognition
TROUBLE SYMPTOM:
CAUTION:
After repair or replacement of faulty parts, conduct Clear Memory Mode ERATION, Clear Memory Mode.> and Inspection Mode tion Mode.>.
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).>
N
OTE:
It is not necessary to
inspect DTC P1110.Replace the ECM.
FU(H4SO)-44,
Engine Control
Module (ECM).>
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).>
N
OTE:
It is not necessary to
inspect DTC P1111.Replace the ECM.
FU(H4SO)-44,
Engine Control
Module (ECM).>

EN(H4SO)-227
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
BT:DTC P1134 A/F SENSOR MICRO-COMPUTER PROBLEM
DTC DETECTING CONDITION:
Immediately at fault recognition
CAUTION:
After repair or replacement of faulty parts, conduct Clear Memory Mode ERATION, Clear Memory Mode.> and Inspection Mode tion Mode.>.
WIRING DIAGRAM:
EN-02384
B18
3412
56
B47F44
12345678
B136B135
1234
B21
123
4
56
78
9
1011 12
1314 15 16
SBF-5
EE
B47
B18
6
4
5
3
2
1
B23 C13
C22C6 C17
C16
C5
8
B:
C:B135
B136
B21
E2 ECMBATTERY
B61F44
7
FRONT OXYGEN
(A/F) SENSOR MAIN RELAY
567
82 1
94
310
24
22 23251112131415
26 27
281617181920 21
5
2
84
3923 20 211011
221617
24
2512136
261915
14
1
7
18
LHDLHD
RHDRHD
4
3
1 2
B: C:

EN(H4SO)-228
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).>
N
OTE:
It is not necessary to
inspect DTC P1134.Replace the ECM.
FU(H4SO)-44,
Engine Control
Module (ECM).>

EN(H4SO)-229
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
BU:DTC P1137 O2 SENSOR CIRCUIT (LAMBDA=1) (BANK 1 SENSOR 1)
DTC DETECTING CONDITION:
Immediately at fault recognition
CAUTION:
After repair or replacement of faulty parts, conduct Clear Memory Mode ERATION, Clear Memory Mode.> and Inspection Mode tion Mode.>.
WIRING DIAGRAM:
EN-02384
B18
3412
56
B47F44
12345678
B136B135
1234
B21
123
4
56
78
9
1011 12
1314 15 16
SBF-5
EE
B47
B18
6
4
5
3
2
1
B23 C13
C22C6 C17
C16
C5
8
B:
C:B135
B136
B21
E2 ECMBATTERY
B61F44
7
FRONT OXYGEN
(A/F) SENSOR MAIN RELAY
567
82 1
94
310
24
22 23251112131415
26 27
281617181920 21
5
2
84
3923 20 211011
221617
24
2512136
261915
14
1
7
18
LHDLHD
RHDRHD
4
3
1 2
B: C:

EN(H4SO)-230
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 FRONT (A/F) OXYGEN SENSOR DA-
TA.
1) Start the engine.
2) While observing the Subaru Select Monitor
or OBD-II general scan tool screen, warm-up
the engine until coolant temperature is above
70°C (160°F).
If the engine is already warmed-up, operate at
idle speed for at least 1 minute.
3) Read the data of front oxygen (A/F) sensor
signal at idling 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 voltage 0.85 — 1.15 V? Go to step 3.Go to step 4.
3 CHECK FRONT (A/F) OXYGEN SENSOR DA-
TA.
Race the engine at speeds from idling to 5,000
rpm for a total of 5 cycles.
N
OTE:
 Normally the air fuel ratio be rich at racing.
 To increase engine speed to 5,000 rpm,
slowly depress accelerator pedal, taking
approximately 5 seconds, and quickly release
accelerator pedal to decrease engine speed.Is the voltage more than 1.1 V? Go to step 6.Go to step 4.
4 CHECK HARNESS BETWEEN ECM AND
FRONT OXYGEN (A/F) SENSOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM and
front oxygen (A/F) sensor connector.
3) Measure the resistance between ECM and
front oxygen (A/F) sensor.
Connector & terminal
(B136) No. 13 — (B18) No. 1:
(B136) No. 22 — (B18) No. 2:Is the resistance less than 5
Ω?Go to step 5.Repair open circuit
between ECM and
front oxygen (A/F)
sensor.
5 CHECK HARNESS BETWEEN ECM AND
FRONT OXYGEN (A/F) SENSOR.
Measure the resistance between ECM and
chassis ground.
Connector & terminal
(B136) No. 13 — Chassis ground:
(B136) No. 22 — Chassis ground:Is the resistance more than 1
MΩ?Go to step 6.Repair ground
short circuit
between ECM and
front oxygen (A/F)
sensor.

EN(H4SO)-231
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
6 CHECK EXHAUST SYSTEM.
Check exhaust system parts.
N
OTE:
Check the following items:
 Loose installation of portions
 Damage (crack, hole etc.) of parts
 Looseness of front oxygen (A/F) sensor
 Looseness and ill fitting of parts between
front oxygen (A/F) sensor and rear oxygen
sensorIs there a fault in exhaust sys-
tem?Repair or replace
the faulty par t.Replace the front
oxygen (A/F) sen-
sor. FU(H4SO)-40,
Front Oxygen (A/
F) Sensor.> Step Check Yes No

EN(H4SO)-232
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
BV:DTC P1492 EGR VALVE SIGNAL #1 CIRCUIT MALFUNCTION (LOW INPUT)
NOTE:
For the diagnostic procedure, refer to DTC P1498. NAL #4 CIRCUIT MALFUNCTION (LOW INPUT), Diagnostic Procedure with Diagnostic Trouble Code
(DTC).>
BW:DTC P1493 EGR VALVE SIGNAL #1 CIRCUIT MALFUNCTION (HIGH INPUT)
NOTE:
For the diagnostic procedure, refer to DTC P1499. NAL #4 CIRCUIT MALFUNCTION (HIGH INPUT), Diagnostic Procedure with Diagnostic Trouble Code
(DTC).>
BX:DTC P1494 EGR VALVE SIGNAL #2 CIRCUIT MALFUNCTION (LOW INPUT)
NOTE:
For the diagnostic procedure, refer to DTC P1498. NAL #4 CIRCUIT MALFUNCTION (LOW INPUT), Diagnostic Procedure with Diagnostic Trouble Code
(DTC).>
BY:DTC P1495 EGR VALVE SIGNAL #2 CIRCUIT MALFUNCTION (HIGH INPUT)
NOTE:
For the diagnostic procedure, refer to DTC P1499. NAL #4 CIRCUIT MALFUNCTION (HIGH INPUT), Diagnostic Procedure with Diagnostic Trouble Code
(DTC).>
BZ:DTC P1496 EGR VALVE SIGNAL #3 CIRCUIT MALFUNCTION (LOW INPUT)
NOTE:
For the diagnostic procedure, refer to DTC P1498. NAL #4 CIRCUIT MALFUNCTION (LOW INPUT), Diagnostic Procedure with Diagnostic Trouble Code
(DTC).>
CA:DTC P1497 EGR VALVE SIGNAL #3 CIRCUIT MALFUNCTION (HIGH INPUT)
NOTE:
For the diagnostic procedure, refer to DTC P1499. NAL #4 CIRCUIT MALFUNCTION (HIGH INPUT), Diagnostic Procedure with Diagnostic Trouble Code
(DTC).>