SUBARU FORESTER 2004 Service Repair Manual

EN(H4DOTC 2.5)-187
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) Place the shift lever except in neutral posi-
tion.
3) Measure the voltage between ECM and
chassis ground.
Connector & terminal
(B137) No. 9 (+) — Chassis ground (
−):Is the voltage less than 1 V? Go to step 2.Go to step 4.
2 CHECK INPUT SIGNAL FROM ECM.
1) Place the shift lever in neutral position.
2) Measure the voltage between ECM and
chassis ground.
Connector & terminal
(B137) No. 9 (+) — Chassis ground (
−):Is the voltage more than 10 V? Go to step 3.Go to step 4.
3 CHECK POOR CONTACT.
Check poor contact in ECM connector.Is there poor contact in ECM
connector?Repair the poor
contact in ECM
connector.Contact the SUB-
ARU dealer.
4 CHECK INPUT SIGNAL FROM ECM.
1) Disconnect the connector from ECM.
2) Measure the voltage between ECM and
chassis ground.
Connector & terminal
(B137) No. 9 (+) — Chassis ground (
−):Is the voltage more than 10 V? Repair battery
short circuit in har-
ness between
ECM and trans-
mission harness
connector.Go to step 5.
5 CHECK HARNESS BETWEEN ECM AND
TRANSMISSION HARNESS CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from ECM and
transmission harness connector (T9).
3) Measure the resistance of harness
between ECM and neutral switch connector.
Connector & terminal
(B137) No. 9 — (B128) No. 1:Is the resistance less than 1
Ω?Go to step 6.Repair the harness
and connector.
N
OTE:
In this case repair
the following:
 Open circuit in
harness between
ECM and trans-
mission harness
connector
 Poor contact in
transmission har-
ness connector.
 Poor contact in
ECM connector.
6 CHECK NEUTRAL POSITION SWITCH
GROUND LINE.
Measure the resistance of harness between
transmission harness connector and engine
ground.
Connector & terminal
(B128) No. 3 — Engine ground:Is the resistance less than 5
Ω?Go to step 7.Repair open circuit
in the neutral posi-
tion switch ground
line.
7 CHECK NEUTRAL POSITION SWITCH.
1) Place the shift lever except in neutral posi-
tion.
2) Measure the resistance between transmis-
sion harness connector socket terminals.
Te r m i n a l s
No. 1 — No. 3:Is the resistance less than 1
Ω?Go to step 8.Replace the neu-
tral position switch.
8 CHECK POOR CONTACT.
Check poor contact in transmission harness
connector.Is there poor contact in trans-
mission harness connector?Repair poor contact
in transmission har-
ness connector.Contact the SUB-
ARU dealer.

EN(H4DOTC 2.5)-188
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
BB:DTC P1086 TUMBLE GENERATED VALVE POSITION SENSOR 2 CIRCUIT
LOW
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 <Ref. to EN(H4DOTC 2.5)-42,
OPERATION, Clear Memory Mode.> and Inspection Mode <Ref. to EN(H4DOTC 2.5)-35, OPERATION,
Inspection Mode.>.
WIRING DIAGRAM:
EN-02371
E3
B22
1
32
B136
16
35 26
B136
E50
123
B22
125678
131415169101112
34
17181920
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
ECM
20
18 10
1 2
B122
E50 TUMBLE GENERATOR VALVE
POSITION SENSOR LH
12345678

EN(H4DOTC 2.5)-189
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 throttle position sensor
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”. <Ref. to EN(H4DOTC
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 voltage less than 0.1 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. A tempo-
rary poor contact
of the connector
may be the cause.
N
OTE:
In this case repair
the following:
 Poor contact in
throttle position
sensor connector
 Poor contact in
ECM connector.
 Poor contact in
coupling connector
2 CHECK INPUT SIGNAL FROM ECM.
Measure the voltage between ECM connector
and chassis ground while tumble generator
valve is fully closed.
Connector & terminal
(B136) No. 16 (+) — Chassis ground (
−):Is the voltage more than 4.5 V? Go to step 4.Go to step 3.
3 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 monitoring
the value with voltage meter?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 INPUT SIGNAL FROM ECM.
Measure the voltage between ECM connector
and chassis ground.
Connector & terminal
(B136) No. 26 (+) — Chassis ground (
−):Is the voltage less than 0.1 V? Go to step 6.Go to step 5.
5 CHECK INPUT SIGNAL FOR ECM WITH
SUBARU SELECT MONITOR.
Measure the voltage between ECM connector
and chassis ground.Does the voltage change by
shaking the harness and con-
nector of ECM while monitoring
the value with Subaru Select
Monitor?Repair the poor
contact in ECM
connector.Go to step 6.

EN(H4DOTC 2.5)-190
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
6 CHECK HARNESS BETWEEN ECM AND
TUMBLE GENERATOR VALVE POSITION
SENSOR CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from tumble gen-
erator valve position sensor.
3) Turn the ignition switch to ON.
4) Measure the voltage between tumble gen-
erator valve position sensor connector and
engine ground.
Connector & terminal
(E50) No. 1 (+) — Engine ground (
−):Is the voltage more than 4.5 V? Go to step 7.Repair the harness
and connector.
N
OTE:
In this case repair
the following:
 Open circuit in
harness between
tumble generator
valve position sen-
sor and ECM con-
nector
 Poor contact in
tumble generator
valve position sen-
sor connector
 Poor contact in
ECM connector.
 Poor contact in
coupling connector
 Poor contact in
joint connector
7 CHECK HARNESS BETWEEN ECM AND
TUMBLE GENERATOR VALVE POSITION
SENSOR CONNECTOR.
1) Turn the ignition switch to OFF.
2) Measure the resistance of harness
between ECM connector and tumble generator
valve position sensor connector.
Connector & terminal
(B136) No. 26 — (E50) No. 3:Is the resistance less than 1
Ω?Go to step 8.Repair the harness
and connector.
N
OTE:
In this case repair
the following:
 Open circuit in
harness between
tumble generator
valve position sen-
sor and ECM con-
nector
 Poor contact in
ECM connector.
 Poor contact in
tumble generator
valve position sen-
sor connector
 Poor contact in
coupling connector
8 CHECK HARNESS BETWEEN ECM AND
TUMBLE GENERATOR VALVE POSITION
SENSOR CONNECTOR.
Measure the resistance of harness between
tumble generator valve position sensor con-
nector and engine ground.
Connector & terminal
(E50) No. 3 — Engine ground:Is the resistance more than 1
MΩ?Go to step 9.Repair ground
short circuit in har-
ness between tum-
ble generator valve
position sensor and
ECM connector.
9 CHECK POOR CONTACT.
Repair poor contact in tumble generator valve
position sensor connector.Is there poor contact in tumble
generator valve position sen-
sor connector?Repair the poor
contact in tumble
generator valve
position sensor
connector.Replace the tum-
ble generator valve
assembly. <Ref. to
FU(H4DOTC 2.5)-
33, Tumble Gener-
ator Valve Assem-
bly.> Step Check Yes No

EN(H4DOTC 2.5)-191
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
BC:DTC P1087 TUMBLE GENERATED VALVE POSITION SENSOR 2 CIRCUIT
HIGH
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 <Ref. to EN(H4DOTC 2.5)-42,
OPERATION, Clear Memory Mode.> and Inspection Mode <Ref. to EN(H4DOTC 2.5)-35, OPERATION,
Inspection Mode.>.
WIRING DIAGRAM:
EN-02371
E3
B22
1
32
B136
16
35 26
B136
E50
123
B22
125678
131415169101112
34
17181920
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
ECM
20
18 10
1 2
B122
E50 TUMBLE GENERATOR VALVE
POSITION SENSOR LH
12345678

EN(H4DOTC 2.5)-192
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 throttle position sensor
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”. <Ref. to EN(H4DOTC
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 voltage more than 4.9 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. A tempo-
rary poor contact
of the connector
may be the cause.
N
OTE:
In this case repair
the following:
 Poor contact in
tumble generator
valve position sen-
sor connector
 Poor contact in
ECM connector.
 Poor contact in
coupling connector
2 CHECK HARNESS BETWEEN TUMBLE
GENERATOR VALVE POSITION SENSOR
AND ECM CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from throttle
position sensor.
3) Measure the resistance of harness
between throttle position sensor connector and
engine ground.
Connector & terminal
(E50) No. 2 — Engine ground:Is the resistance less than 5
Ω?Go to step 3.Repair the harness
and connector.
N
OTE:
In this case repair
the following:
 Open circuit in
harness between
tumble generator
valve position sen-
sor and ECM con-
nector
 Poor contact in
coupling connector
 Poor contact in
joint connector
3 CHECK HARNESS BETWEEN THROTTLE
POSITION SENSOR AND ECM CONNEC-
TOR.
1) Turn the ignition switch to ON.
2) Measure the voltage between throttle posi-
tion sensor connector and engine ground.
Connector & terminal
(E50) No. 3 (+) — Engine ground (
−):Is the voltage more than 4.9 V? Repair battery
short circuit in har-
ness between tum-
ble generator valve
position sensor
and ECM connec-
tor. After repair,
replace the ECM.
<Ref. to
FU(H4DOTC 2.5)-
41, Engine Con-
trol Module
(ECM).>Replace the tum-
ble generator valve
assembly. <Ref. to
FU(H4DOTC 2.5)-
33, Tumble Gener-
ator Valve Assem-
bly.>

EN(H4DOTC 2.5)-193
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
BD:DTC P1088 TUMBLE GENERATED VALVE POSITION SENSOR 1 CIRCUIT
LOW
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 <Ref. to EN(H4DOTC 2.5)-42,
OPERATION, Clear Memory Mode.> and Inspection Mode <Ref. to EN(H4DOTC 2.5)-35, OPERATION,
Inspection Mode.>.
WIRING DIAGRAM:
EN-02372
E54
123
B22
125678
131415169101112
34
17181920
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
ECM TUMBLE GENERATOR VALVE
POSITION SENSOR RH
E3
B22
1
32
B136
16
35 27
20
189
1 2
B122
E54
12345678

EN(H4DOTC 2.5)-194
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 tumble generator valve
position sensor 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”. <Ref. to EN(H4DOTC
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 voltage less than 0.1 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. A tempo-
rary poor contact
of the connector
may be the cause.
N
OTE:
In this case repair
the following:
 Poor contact in
tumble generator
valve position sen-
sor connector
 Poor contact in
ECM connector.
 Poor contact in
coupling connector
2 CHECK INPUT SIGNAL FROM ECM.
Measure the voltage between ECM connector
and chassis ground while throttle valve is fully
closed.
Connector & terminal
(B136) No. 16 (+) — Chassis ground (
−):Is the voltage more than 4.5 V? Go to step 4.Go to step 3.
3 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 monitoring
the value with voltage meter?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 INPUT SIGNAL FROM ECM.
Measure the voltage between ECM connector
and chassis ground.
Connector & terminal
(B136) No. 27 (+) — Chassis ground (
−):Is the voltage less than 0.1 V? Go to step 6.Go to step 5.
5 CHECK INPUT SIGNAL FOR ECM WITH
SUBARU SELECT MONITOR.
Measure the voltage between ECM connector
and chassis ground.Does the voltage change by
shaking the harness and con-
nector of ECM while monitoring
the value with Subaru Select
Monitor?Repair the poor
contact in ECM
connector.Go to step 6.

EN(H4DOTC 2.5)-195
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
6 CHECK HARNESS BETWEEN ECM AND
TUMBLE GENERATOR VALVE POSITION
SENSOR CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from throttle
position sensor.
3) Turn the ignition switch to ON.
4) Measure the voltage between throttle posi-
tion sensor connector and engine ground.
Connector & terminal
(E54) No. 1 (+) — Engine ground (
−):Is the voltage more than 4.5 V? Go to step 7.Repair the harness
and connector.
N
OTE:
In this case repair
the following:
 Open circuit in
harness between
tumble generator
valve position sen-
sor and ECM con-
nector
 Poor contact in
throttle position
sensor connector
 Poor contact in
ECM connector.
 Poor contact in
coupling connector
 Poor contact in
joint connector
7 CHECK HARNESS BETWEEN ECM AND
TUMBLE GENERATOR VALVE POSITION
SENSOR CONNECTOR.
1) Turn the ignition switch to OFF.
2) Measure the resistance of harness
between ECM connector and throttle position
sensor connector.
Connector & terminal
(B136) No. 27 — (E54) No. 3:Is the resistance less than 1
Ω?Go to step 8.Repair the harness
and connector.
NOTE:
In this case repair
the following:
 Open circuit in
harness between
tumble generator
valve position sen-
sor and ECM con-
nector
 Poor contact in
ECM connector.
 Poor contact in
tumble generator
valve position sen-
sor connector
 Poor contact in
coupling connector
8 CHECK HARNESS BETWEEN ECM AND
THROTTLE POSITION SENSOR CONNEC-
TOR.
Measure the resistance of harness between
tumble generator valve position sensor con-
nector and engine ground.
Connector & terminal
(E54) No. 3 — Engine ground:Is the resistance more than 1
MΩ?Go to step 9.Repair ground
short circuit in har-
ness between tum-
ble generator valve
position sensor and
ECM connector.
9 CHECK POOR CONTACT.
Repair poor contact in tumble generator valve
position sensor connector.Is there poor contact in tumble
generator valve position sen-
sor connector?Repair the poor
contact in tumble
generator valve
position sensor
connector.Replace the tum-
ble generator valve
assembly. <Ref. to
FU(H4DOTC 2.5)-
33, Tumble Gener-
ator Valve Assem-
bly.> Step Check Yes No

EN(H4DOTC 2.5)-196
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
BE:DTC P1089 TUMBLE GENERATED VALVE POSITION SENSOR 1 CIRCUIT
HIGH
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 <Ref. to EN(H4DOTC 2.5)-42,
OPERATION, Clear Memory Mode.> and Inspection Mode <Ref. to EN(H4DOTC 2.5)-35, OPERATION,
Inspection Mode.>.
WIRING DIAGRAM:
EN-02372
E54
123
B22
125678
131415169101112
34
17181920
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
ECM TUMBLE GENERATOR VALVE
POSITION SENSOR RH
E3
B22
1
32
B136
16
35 27
20
189
1 2
B122
E54
12345678