SUBARU FORESTER 2004 Service Repair Manual

EN(H4DOTC)-98
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
P0101.Replace the mass
air flow and intake
air temperature
sensor. FU(H4DOTC)-35,
Mass Air Flow and
Intake Air Temper-
ature Sensor.>

EN(H4DOTC)-99
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
J: DTC P0102MASS OR VOLUME AIR FLOW CIRCUIT LOW INPUT
DTC DETECTING CONDITION:
Immediately at fault recognition
TROUBLE SYMPTOM:
 Erroneous idling
 Engine stalls.
 Poor driving performance
WIRING DIAGRAM:
EN-02324
B122B3
BATTERY
E
B61F44
7LHD
RHD
LHD
RHD
1
B3
MASS AIR FLOW AND INTAKE
AIR TEMPERATURE SENSOR
ECMB136
SBF-5
123453412
56
B47 1
2
*
*
2 4 3 5
311323 3532LHD : 8
RHD : 5
LHD : 1
RHD : 1*1
*2
F44
12345678
MAIN RELAY
B47 1 2 3 5 4 6
12345678
B136 B122
56
782 1
94 310
24 22 23 2511 12 13
1415
26 27
2816
17 18 19 20 21
33 34 29
32 30
31 35

EN(H4DOTC)-100
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step Check Yes No
1 CONNECT SUBARU SELECT MONITOR OR
THE OBD-II GENERAL SCAN TOOL, AND
READ DATA.
1) Turn the ignition switch to OFF.
2) Connect the Subaru Select Monitor or the
OBD-II general scan tool to data link connec-
tor.
3) Turn the ignition switch to ON and the Sub-
aru Select Monitor or OBD-II general scan tool
switch to ON.
4) Start the engine.
5) Connect the Subaru Select Monitor or
OBD-II general scan tool, and read the mass
air flow sensor voltage.
N
OTE:
 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 voltage 0.2 — 4.7 V? Even if the mal-
function indicator
light illuminates,
the circuit has
returned to a nor-
mal condition at
this time.A tempo-
rary poor contact
of the connector or
harness may be
the cause.Repair
harness or con-
nector in the mass
air flow sensor.
NOTE:
In this case repair
the following:
 Open or ground
short circuit in har-
ness between
mass air flow sen-
sor and ECM con-
nector
 Poor contact in
mass air flow sen-
sor or ECM con-
nectorGo to step 2.
2 CHECK INPUT SIGNAL FROM ECM.
Measure the voltage between ECM connector
and chassis ground while engine is idling.
Connector & terminal
(B136) No. 23 (+) — Chassis ground (
−):Is the voltage more than 0.2 V? Go to step 4.Go to step 3.
3 CHECK INPUT SIGNAL FOR ECM (WITH
SUBARU SELECT MONITOR).
Measure the voltage between ECM connector
and chassis ground while engine is idling.Does the voltage change by
shaking the harness and con-
nector of ECM while monitor-
ing the value with Subaru
Select Monitor?Repair the poor
contact in ECM
connector.Contact the SUB-
ARU dealer.
N
OTE:
Inspection by DTM
is required, because
probable cause is
deterioration of mul-
tiple parts.
4 CHECK POWER SUPPLY TO MASS AIR
FLOW SENSOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from mass air
flow sensor.
3) Turn the ignition switch to ON.
4) Measure voltage between mass air flow
sensor connector and chassis ground.
Connector & terminal
(B3) No. 1 (+) — Chassis ground (
−):Is the voltage more than 5 V? Go to step 5.Repair open circuit
between mass air
flow sensor and
main relay

EN(H4DOTC)-101
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
5 CHECK HARNESS BETWEEN ECM AND
MASS AIR FLOW SENSOR CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Measure the resistance of harness
between ECM and mass air flow sensor con-
nector.
Connector & terminal
(B136) No. 23 — (B3) No. 3:
(B136) No. 31 — (B3) No. 2:
(B135) No. 35 — (B3) No. 5:Is the resistance less than 1
Ω?Go to step 6.Repair open circuit
between ECM and
mass air flow sen-
sor connector.
6 CHECK HARNESS BETWEEN ECM AND
MASS AIR FLOW SENSOR CONNECTOR.
Measure the resistance of harness between
ECM and chassis ground.
Connector & terminal
(B136) No. 23 — Chassis ground:
(B136) No. 31 — Chassis ground:
(B135) No. 35 — Chassis ground:Is the resistance more than 1
MΩ?Go to step 7.Repair ground
short circuit
between ECM and
mass air flow sen-
sor connector.
7 CHECK POOR CONTACT.
Check poor contact in mass air flow sensor
connector.Is there poor contact in mass
air flow sensor connector?Repair poor con-
tact in mass air
flow sensor con-
nector.Replace the mass
air flow and intake
air temperature
sensor. FU(H4DOTC)-35,
Mass Air Flow and
Intake Air Temper-
ature Sensor.> Step Check Yes No

EN(H4DOTC)-102
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
K: DTC P0103 MASS OR VOLUME AIR FLOW CIRCUIT HIGH INPUT
DTC DETECTING CONDITION:
Immediately at fault recognition
TROUBLE SYMPTOM:
 Erroneous idling
 Engine stalls.
 Poor driving performance
CAUTION:
After repair or replacement of faulty parts, conduct Clear Memory Mode ERATION, Clear Memory Mode.> and Inspection Mode .
WIRING DIAGRAM:
EN-02324
B122B3
BATTERY
E
B61F44
7LHD
RHD
LHD
RHD
1
B3
MASS AIR FLOW AND INTAKE
AIR TEMPERATURE SENSOR
ECMB136
SBF-5
123453412
56
B47 1
2
*
*
2 4 3 5
311323 3532LHD : 8
RHD : 5
LHD : 1
RHD : 1*1
*2
F44
12345678
MAIN RELAY
B47 1 2 3 5 4 6
12345678
B136 B122
56
782 1
94 310
24 22 23 2511 12 13
1415
26 27
2816
17 18 19 20 21
33 34 29
32 30
31 35

EN(H4DOTC)-103
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step Check Yes No
1 CONNECT SUBARU SELECT MONITOR OR
THE OBD-II GENERAL SCAN TOOL, AND
READ DATA.
1) Turn the ignition switch to OFF.
2) Connect the Subaru Select Monitor or the
OBD-II general scan tool to data link connec-
tor.
3) Turn the ignition switch to ON and the Sub-
aru Select Monitor or OBD-II general scan tool
switch to ON.
4) Start the engine.
5) Connect the Subaru Select Monitor or
OBD-II general scan tool, and read the mass
air flow sensor voltage.
N
OTE:
 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 voltage 0.2 — 4.7 V? Even if the mal-
function indicator
light illuminates,
the circuit has
returned to a nor-
mal condition at
this time.Go to step 2.
2 CHECK HARNESS BETWEEN ECM AND
MASS AIR FLOW SENSOR CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from mass air-
flow sensor.
3) Turn the ignition switch to ON.
4) Measure voltage between mass air flow
sensor connector and chassis ground.
Connector & terminal
(B3) No. 3 (+) — Chassis ground (
−):Is the voltage more than 5 V? Repair battery
short circuit in har-
ness between
mass air flow sen-
sor connector and
ECM connector. Go to step 3.
3 CHECK HARNESS BETWEEN ECM AND
MASS AIR FLOW SENSOR CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Measure the resistance of harness
between ECM connector and mass air flow
sensor connector.
Connector & terminal
(B3) No. 2 — (B136) No. 31:Is the resistance less than 1
Ω?Replace the mass
air flow sensor.
FU(H4DOTC)-35,
Mass Air Flow and
Intake Air Temper-
ature Sensor.>Repair open circuit
in harness
between mass air
flow sensor con-
nector and ECM
connector.

EN(H4DOTC)-104
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
L: DTC P0107 MANIFOLD ABSOLUTE PRESSURE/BAROMETRIC PRESSURE
CIRCUIT LOW INPUT
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 .
WIRING DIAGRAM:
LHD model
EN-02322
B122 MANIFOLD
ABSOLUTE
PRESSURE
SENSORTHROTTLE BODY
2 3
1 16
35
22
ECMB136
E21
E2
F61
2
118 20
16
F74
B20016
21
123
F61E21
1
25678
131415169101112
34
17181920
B136F2B122
F74
56
782 1
94 310
24 22 23 2511 12 13
1415
26 27
2816
17 18 19 20 21
33 34 29
32 30
31 35
34
12 8910 11
12 13 14 15 16 17 18 19 20 21 22 23 2456 7
123456781234 5678910 11 12 13 14 15 16 17 18 19 20
F2
B1007

EN(H4DOTC)-105
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
RHD model
EN-02323
B122
MANIFOLD
ABSOLUTE
PRESSURE
SENSORTHROTTLE BODY
3 2
1 35
16
22
ECMB136
E21
E3
B22
2
120 18
16
123
B122B22E21
1
25678
131415169101112
34
17181920
B136
1234567856
782 1
94 310
24 22 23 2511 12 13
1415
26 27
2816
17 18 19 20 21
33 34 29
32 30
31 35

EN(H4DOTC)-106
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. 16 (+) — Chassis ground (
−):Is the voltage more than 4.5 V? Go to step 3.Go to step 2.
2 CHECK INPUT SIGNAL FROM ECM.
Measure the voltage between ECM connector
and chassis ground.
Connector & terminal
(B136) No. 16 (+) — Chassis ground (
−):Does the voltage change by
shaking the harness and con-
nector of ECM while monitor-
ing the value with voltage
meter?Repair the poor
contact in ECM
connector.Contact the SUB-
ARU dealer.
N
OTE:
Inspection by DTM
is required, be-
cause probable
cause is deteriora-
tion of multiple
parts.
3 CHECK INPUT SIGNAL FROM ECM.
Measure the voltage between ECM and chas-
sis ground.
Connector & terminal
(B136) No. 22 (+) — Chassis ground (
−):Is the voltage less than 0.7 V? Go to step 4.Contact the SUB-
ARU dealer.
N
OTE:
Inspection by DTM
is required, be-
cause probable
cause is deteriora-
tion of multiple
parts.
4 CHECK HARNESS BETWEEN ECM AND
MANIFOLD ABSOLUTE PRESSURE SEN-
SOR CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from the manifold
absolute pressure sensor.
3) Turn the ignition switch to ON.
4) Measure the voltage between manifold
absolute pressure sensor connector and
engine ground.
Connector & terminal
(E21) No. 3 (+) — Engine ground (
−):Is the voltage more than 4.5 V? Go to step 5.Repair the open
circuit in harness
between ECM and
manifold absolute
pressure sensor
connector.
5 CHECK HARNESS BETWEEN ECM AND
MANIFOLD ABSOLUTE PRESSURE SEN-
SOR CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Measure the resistance of harness
between ECM and manifold absolute pressure
sensor connector.
Connector & terminal
(B136) No. 35 — (E21) No. 2:Is the resistance less than 1
Ω?Go to step 6.Repair the open
circuit in harness
between ECM and
manifold absolute
pressure sensor
connector.
6 CHECK HARNESS BETWEEN ECM AND
MANIFOLD ABSOLUTE PRESSURE SEN-
SOR CONNECTOR.
Measure the resistance of harness between
manifold absolute pressure sensor connector
and engine ground.
Connector & terminal
(E21) No. 1 — Engine ground:Is the resistance more than 1
MΩ?Go to step 7.Repair the ground
short circuit in har-
ness between
ECM and mani-
fold absolute pres-
sure sensor
connector.
7 CHECK POOR CONTACT.
Check poor contact in manifold absolute pres-
sure sensor connector.Is there poor contact in mani-
fold absolute pressure sensor
connector?Repair poor con-
tact in manifold
absolute pressure
sensor connector.Replace the mani-
fold absolute pres-
sure sensor. to FU(H4DOTC)-
36, Manifold Abso-
lute Pressure Sen-
sor.>

EN(H4DOTC)-107
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
M: DTC P0108 INTAKE AIR PRESSURE SENSOR CIRCUIT HIGH INPUT
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 .
WIRING DIAGRAM:
LHD model
EN-02322
B122 MANIFOLD
ABSOLUTE
PRESSURE
SENSORTHROTTLE BODY
2 3
1 16
35
22
ECMB136
E21
E2
F61
2
118 20
16
F74
B20016
21
123
F61E21
1
25678
131415169101112
34
17181920
B136F2B122
F74
56
782 1
94 310
24 22 23 2511 12 13
1415
26 27
2816
17 18 19 20 21
33 34 29
32 30
31 35
34
12 8910 11
12 13 14 15 16 17 18 19 20 21 22 23 2456 7
123456781234 5678910 11 12 13 14 15 16 17 18 19 20
F2
B1007