2004 SUBARU FORESTER relay

EN(H4DOTC 2.5)-77
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
6 CHECK POWER SUPPLY TO REAR OXY-
GEN SENSOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from rear oxygen
sensor.
3) Turn the ignition switch to ON.
4) Measure the voltage between rear oxygen
sensor connector and chassis ground.
Connector & terminal
(B18) No. 2 (+) — Chassis ground (
−):Is the voltage more than 10 V? Go to step 7.Repair the power
supply line.
N
OTE:
In this case repair
the following:
 Open circuit in
harness between
main relay and
rear oxygen sen-
sor connector
 Poor contact in
rear oxygen sen-
sor connector
 Poor contact in
coupling connector
7 CHECK REAR OXYGEN SENSOR.
1) Turn the ignition switch to OFF.
2) Measure the resistance between rear oxy-
gen sensor connector terminals.
Te r m i n a l s
No. 1 — No. 2:Is the resistance less than 30
Ω?Repair the harness
and connector.
N
OTE:
In this case repair
the following:
 Open circuit in
harness between
rear oxygen sen-
sor and ECM con-
nector
 Poor contact in
rear oxygen sen-
sor connector
 Poor contact in
ECM connector
 Poor contact in
coupling connectorReplace the rear
oxygen sensor.
FU(H4DOTC 2.5)-
38, Rear Oxygen
Sensor.> Step Check Yes No

EN(H4DOTC 2.5)-78
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
D: DTC P0038 HO2S HEATER CONTROL CIRCUIT HIGH (BANK 1 SENSOR 2)
DTC DETECTING CONDITION:
Immediately at fault recognition
CAUTION:
After repair or replacement of faulty parts, conduct Clear Memory Mode OPERATION, Clear Memory Mode.> and Inspection Mode Inspection Mode.>.
WIRING DIAGRAM:
EN-02360
B122 B47 1 2 3 5 4 6
E
E
B21
E23
4
1
B122
34 12
56123
4
56
78
9
1011 12
1314 15 16
: B134
: B135B21
B47 T6
: B136 T6
A6
A7B2
D25
D31
C35
C : B :
D :
4
6
B83A
B
C
B136
B137 B135 B134 A :
: B137
D
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
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
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
ECM MAIN RELAYBATTERY
REAR OXYGEN
SENSOR
12345678
B18 T52
B18
T5
B18
1234
B83
1
23456
1234
3 1
4
1
2
4
3

EN(H4DOTC 2.5)-80
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
E: DTC P0102 MASS 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-02361
B3
E
B122
1
B3
ECM
B136SBF-5
1234
5
34 12
56
B136
B47 5
1
2 4 3 5
31 1323 35
32
B47 1 2 3 5 4 6
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
BATTERY MAIN RELAY
MASS AIR FLOW AND
INTAKE AIR TEMPERATURE
SENSOR
12345678

EN(H4DOTC 2.5)-81
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 connector.
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 DISPLAY FOR
ENGINE”. aru 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.
N
OTE:
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
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 connector.
Connector & terminal
(B136) No. 23 — (B3) No. 3:
(B136) No. 31 — (B3) No. 2:
(B136) 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.

EN(H4DOTC 2.5)-83
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
F: 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 OPERATION, Clear Memory Mode.> and Inspection Mode Inspection Mode.>.
WIRING DIAGRAM:
EN-02361
B3
E
B122
1
B3
ECM
B136SBF-5
1234
5
34 12
56
B136
B47 5
1
2 4 3 5
31 1323 35
32
B47 1 2 3 5 4 6
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
BATTERY MAIN RELAY
MASS AIR FLOW AND
INTAKE AIR TEMPERATURE
SENSOR
12345678

EN(H4DOTC 2.5)-89
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
I: DTC P0112 INTAKE AIR TEMPERATURE CIRCUIT LOW INPUT
DTC DETECTING CONDITION:
Immediately at fault recognition
TROUBLE SYMPTOM:
 Erroneous idling
 Poor driving performance
CAUTION:
After repair or replacement of faulty parts, conduct Clear Memory Mode OPERATION, Clear Memory Mode.> and Inspection Mode Inspection Mode.>.
WIRING DIAGRAM:
EN-02361
B3
E
B122
1
B3
ECM
B136SBF-5
1234
5
34 12
56
B136
B47 5
1
2 4 3 5
31 1323 35
32
B47 1 2 3 5 4 6
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
BATTERY MAIN RELAY
MASS AIR FLOW AND
INTAKE AIR TEMPERATURE
SENSOR
12345678

EN(H4DOTC 2.5)-91
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
J: DTC P0113 INTAKE AIR TEMPERATURE CIRCUIT HIGH INPUT
DTC DETECTING CONDITION:
Immediately at fault recognition
TROUBLE SYMPTOM:
 Erroneous idling
 Poor driving performance
CAUTION:
After repair or replacement of faulty parts, conduct Clear Memory Mode OPERATION, Clear Memory Mode.> and Inspection Mode Inspection Mode.>.
WIRING DIAGRAM:
EN-02361
B3
E
B122
1
B3
ECM
B136SBF-5
1234
5
34 12
56
B136
B47 5
1
2 4 3 5
31 1323 35
32
B47 1 2 3 5 4 6
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
BATTERY MAIN RELAY
MASS AIR FLOW AND
INTAKE AIR TEMPERATURE
SENSOR
12345678

EN(H4DOTC 2.5)-100
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
WIRING DIAGRAM:
EN-02364
B317
34
12
B22
125678
131415169101112
34
17181920
B21
123
4
56
78
9
1011 12
1314 15 16
B83
1
23456
B135
567
82 1
94 3
10
24 22 23 2511 12 13 14 15
26 27
2816 17 18 19
20 21
29 30 31 32 33 34 35
B:
B35D6
B135 B: C:
D4 D3
C18
B1 C35
D1 B4
D2
SBF-5
2
1
3
4
E
E57
3
6 4
1
2 2
3
15
16
E
5
EE
B137 D:ECM B309
B136
B122
1
E2 B21
E3 B22 B317
E56B47 35
2 1
4 3
D5C16C29
19122018
MAIN RELAYBATTERY
ELECTRONIC
THROTTLE
CONTROL ELECTRONIC
THROTTLE
CONTROL
RELAY
B83
B122
123456783412
56
B47
B137
567
82 1
94 3
10
22 23 11 12 13 14 15
24 25
2616 17
18 19 20 21
27 28 29 30 31
D:
B136
56
782 1
94 3
10
24 22 23 2511 12 13
1415
26 27
2816
17 18 19 20 21
33 34 29
32 30
31 35
C:
B309
34
12
E57