ECU SUBARU FORESTER 2004 Service Repair Manual

EN(H4DOTC)-176
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).>Go to step 2.
2 CHECK CONDITION OF CRANKSHAFT PO-
SITION SENSOR.
Turn the ignition switch to OFF.Is the crankshaft position sen-
sor installation bolt tightened
securely?Go to step 3.Tighten the crank-
shaft position sen-
sor installation bolt
securely.
3 CHECK CRANK SPROCKET.
Remove the front belt cover.Are crank sprocket teeth
cracked or damaged?Replace the crank
sprocket. ME(H4DOTC)-67,
Crank Sprocket.>Go to step 4.
4 CHECK INSTALLATION CONDITION OF
TIMING BELT.
Turn the crankshaft, and align alignment mark
on crank sprocket with alignment mark on cyl-
inder block.Is the timing belt dislocated
from its proper position?Repair installation
condition of timing
belt. ME(H4DOTC)-58,
Timing Belt
Assembly.>Replace the crank-
shaft position sen-
sor. FU(H4DOTC)-30,
Crankshaft Posi-
tion Sensor.>

EN(H4DOTC)-178
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step Check Yes No
1 CHECK HARNESS BETWEEN CAMSHAFT
POSITION SENSOR CONNECTOR AND ECM
CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from camshaft
position sensor connector.
3) Measure the resistance of harness
between camshaft position sensor connector
and engine ground.
Connector & terminal
(E15) No. 1 — Engine ground:Is the resistance more than
100 kΩ?Repair the har-
ness and connec-
tor.
N
OTE:
In this case repair
the following:
 Open circuit in
harness between
camshaft position
sensor connector
and ECM connec-
tor
 Poor contact in
ECM connector.
 Poor contact in
coupling connectorGo to step 2.
2 CHECK HARNESS BETWEEN CAMSHAFT
POSITION SENSOR CONNECTOR AND ECM
CONNECTOR.
Measure the resistance of harness between
camshaft position sensor connector and
engine ground.
Connector & terminal
(E15) No. 1 — Engine ground:Is the resistance less than 10
Ω?Repair ground
short circuit in har-
ness between
camshaft position
sensor connector
and ECM connec-
tor.
N
OTE:
The harness be-
tween both con-
nectors are
shielded.Repair
ground short circuit
in harness togeth-
er with shield.Go to step 3.
3 CHECK HARNESS BETWEEN CAMSHAFT
POSITION SENSOR CONNECTOR AND ECM
CONNECTOR.
Measure the resistance of harness between
camshaft position sensor connector and
engine ground.
Connector & terminal
(E15) No. 2 — Engine ground:Is the resistance less than 5
Ω?Go to step 4.Repair the har-
ness and connec-
tor.
N
OTE:
In this case repair
the following:
 Open circuit in
harness between
camshaft position
sensor connector
and ECM connec-
tor
 Poor contact in
ECM connector
 Poor contact in
coupling connector
4 CHECK CONDITION OF CAMSHAFT POSI-
TION SENSOR CONNECTOR.Is the camshaft position sensor
connector installation bolt tight-
ened securely?Go to step 5.Tighten the cam-
shaft position sen-
sor connector
installation bolt
securely.
5 CHECK CAMSHAFT POSITION SENSOR
CONNECTOR.
1) Remove the camshaft position sensor con-
nector.
2) Measure the resistance between connector
terminals of camshaft position sensor connector.
Te r m i n a l s
No. 1 — No. 2:Is the resistance 1 — 4 kΩ? Repair poor con-
tact in camshaft
position sensor
connector.Replace the cam-
shaft position sen-
sor connector.
FU(H4DOTC)-31,
Camshaft Position
Sensor.>

EN(H4DOTC)-179
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
AT:DTC P0341 CAMSHAFT POSITION SENSOR “A” CIRCUIT RANGE/PERFOR-
MANCE (BANK 1 OR SINGLE SENSOR)
DTC DETECTING CONDITION:
Two consecutive driving cycles with fault
TROUBLE SYMPTOM:
 Engine stalls.
 Failure of engine to start
CAUTION:
After repair or replacement of faulty parts, conduct Clear Memory Mode ERATION, Clear Memory Mode.> and Inspection Mode .
WIRING DIAGRAM:
EN-02331
4
3E1
E15
B20
2
1
B135 ECM
23
31 11
E
E15
12
12 34
56
7
89
10
B20
B135
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
AVCS
CAMSHAFT
POSITION
SENSOR

EN(H4DOTC)-181
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
5 CHECK CONDITION OF CAMSHAFT POSI-
TION SENSOR CONNECTOR.Is the camshaft position sensor
connector installation bolt tight-
ened securely?Go to step 6.Tighten the cam-
shaft position sen-
sor connector
installation bolt
securely.
6 CHECK CAMSHAFT POSITION SENSOR
CONNECTOR.
1) Remove the camshaft position sensor con-
nector.
2) Measure the resistance between connector
terminals of camshaft position sensor connec-
tor.
Te r m i n a l s
No. 1 — No. 2:Is the resistance 1 — 4 kΩ? Go to step 7.Replace the cam-
shaft position sen-
sor connector.
FU(H4DOTC)-31,
Camshaft Position
Sensor.>
7 CHECK CONDITION OF CAMSHAFT POSI-
TION SENSOR CONNECTOR.
Turn the ignition switch to OFF.Is the camshaft position sensor
connector installation bolt tight-
ened securely?Go to step 8.Tighten the cam-
shaft position sen-
sor connector
installation bolt
securely.
8 CHECK CAM SPROCKET.
Remove the front belt cover. ME(H4DOTC)-57, Timing Belt Cover.>Are cam sprocket teeth
cracked or damaged?Replace the cam
sprocket. ME(H4DOTC)-66,
Cam Sprocket.>Go to step 9.
9 CHECK INSTALLATION CONDITION OF
TIMING BELT.
Turn the crankshaft, and align alignment mark
on camshaft sprocket with alignment mark on
timing belt cover LH.Is the timing belt dislocated
from its proper position?Repair installation
condition of timing
belt. ME(H4DOTC)-58,
Timing Belt
Assembly.>Replace the cam-
shaft position sen-
sor connector.
FU(H4DOTC)-31,
Camshaft Position
Sensor.> Step Check Yes No

EN(H4DOTC)-183
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step Check Yes No
1 CHECK CURRENT DATA.
1) Start the engine.
2) Drive the vehicle at the speed of approx. 30
km/h (19 MPH), and then measure the ignition
timing advance angle 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”. 33, Subaru Select Monitor.>
 OBD-II general scan tool
For detailed operation procedures, refer to the
OBD-II General Scan Tool Operation Manual.Does the ignition timing
advance angle changed
smoothly according to engine
output?
Idling: −2 — +2°
Driving: −2 — +50°Repair the poor
contact connector.
N
OTE:
In this case, repair
the following:
 Poor contact of
AVCS camshaft
position sensor
connector.
 Poor contact in
ECM connector.Go to step 2.
2 CHECK HARNESS BETWEEN AVCS CAM-
SHAFT POSITION SENSOR CONNECTOR
AND ECM CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from AVCS cam-
shaft position sensor connector and ECM.
3) Measure the resistance of harness
between AVCS camshaft position sensor con-
nector and engine ground.
Connector & terminal
(B36) No. 1 — (B135) No. 21:
(B36) No. 2 — (B135) No. 29:Is the resistance less than 1
Ω?Go to step 3.Repair the har-
ness and connec-
tor.
N
OTE:
In this case, repair
the following:
 Open circuit in
harness between
AVCS camshaft
position sensor
connector and
ECM connector
 Poor contact in
ECM connector
 Poor contact in
coupling connector
3 CHECK HARNESS BETWEEN AVCS CAM-
SHAFT POSITION SENSOR CONNECTOR
AND ECM CONNECTOR.
Measure the resistance of harness between
AVCS camshaft position sensor connector and
engine ground.
Connector & terminal
(E36) No. 1 — Engine ground:
(E36) No. 2 — Engine ground:Is the resistance more than 1
MΩ?Go to step 4.Repair the ground
short circuit in har-
ness between
AVCS camshaft
position sensor
connector and
ECM connector.
NOTE:
The harness be-
tween both con-
nectors are
shielded.Repair
ground short circuit
in harness togeth-
er with shield.
4 CHECK CONDITION OF AVCS CAMSHAFT
POSITION SENSOR CONNECTOR.Is the AVCS camshaft position
sensor connector installation
bolt tightened securely?Go to step 5.Tighten the AVCS
camshaft position
sensor connector
installation bolt
securely.
5 CHECK AVCS CAMSHAFT POSITION SEN-
SOR CONNECTOR.
1) Remove the AVCS camshaft position sen-
sor.
2) Measure the resistance between the AVCS
camshaft position sensor connector terminals.
Te r m i n a l s
No. 1 — No. 2:Is the resistance 1 — 4 kΩ? Check for the clog-
ging on oil pres-
sure routing of oil
flow control sole-
noid valve.Replace the AVCS
camshaft position
sensor connector.
FU(H4DOTC)-32,
AVCS Camshaft
Position Sensor.>

EN(H4DOTC)-185
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step Check Yes No
1 CHECK CURRENT DATA.
1) Start the engine.
2) Drive the vehicle at the speed of approx. 30
km/h (19 MPH), and then measure the ignition
timing advance angle 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”. 33, Subaru Select Monitor.>
 OBD-II general scan tool
For detailed operation procedures, refer to the
OBD-II General Scan Tool Operation Manual.Does the ignition timing
advance angle changed
smoothly according to engine
output?
Idling: −2 — +2°
Driving: −2 — +50°Repair the poor
contact connector.
N
OTE:
In this case, repair
the following:
 Poor contact of
AVCS camshaft
position sensor
connector.
 Poor contact in
ECM connector.Go to step 2.
2 CHECK HARNESS BETWEEN AVCS CAM-
SHAFT POSITION SENSOR CONNECTOR
AND ECM CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from AVCS cam-
shaft position sensor connector and ECM.
3) Measure the resistance of harness
between AVCS camshaft position sensor con-
nector and engine ground.
Connector & terminal
(B35) No. 1 — (B135) No. 20:
(B35) No. 2 — (B135) No. 28:Is the resistance less than 1
Ω?Go to step 3.Repair the har-
ness and connec-
tor.
N
OTE:
In this case, repair
the following:
 Open circuit in
harness between
AVCS camshaft
position sensor
connector and
ECM connector
 Poor contact in
ECM connector.
 Poor contact in
coupling connector
3 CHECK HARNESS BETWEEN AVCS CAM-
SHAFT POSITION SENSOR CONNECTOR
AND ECM CONNECTOR.
Measure the resistance of harness between
AVCS camshaft position sensor connector and
engine ground.
Connector & terminal
(E35) No. 1 — Engine ground:
(E35) No. 2 — Engine ground:Is the resistance more than 1
MΩ?Go to step 4.Repair the ground
short circuit in har-
ness between
AVCS camshaft
position sensor
connector and
ECM connector.
NOTE:
The harness be-
tween both con-
nectors are
shielded.Repair
ground short circuit
in harness togeth-
er with shield.
4 CHECK CONDITION OF AVCS CAMSHAFT
POSITION SENSOR CONNECTOR.Is the AVCS camshaft position
sensor connector installation
bolt tightened securely?Go to step 5.Tighten the AVCS
camshaft position
sensor connector
installation bolt
securely.
5 CHECK AVCS CAMSHAFT POSITION SEN-
SOR CONNECTOR.
1) Remove the AVCS camshaft position sen-
sor connector.
2) Measure the resistance between the AVCS
camshaft position sensor connector terminals.
Te r m i n a l s
No. 1 — No. 2:Is the resistance 1 — 4 kΩ? Check for the oil
clogging on oil
pressure routing of
oil flow control
solenoid valve.Replace the AVCS
camshaft position
sensor connector.
FU(H4DOTC)-32,
AVCS Camshaft
Position Sensor.>

EN(H4DOTC)-186
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
AW:DTC P0420 CATALYST SYSTEM EFFICIENCY BELOW THRESHOLD (BANK
1)
DTC DETECTING CONDITION:
Two consecutive driving cycles with fault
TROUBLE SYMPTOM:
 Engine stalls.
 Idle mixture is out of specifications.
CAUTION:
After repair or replacement of faulty parts, conduct Clear Memory Mode ERATION, Clear Memory Mode.> and Inspection Mode .
WIRING DIAGRAM:
EN-02334
BATTERY
MAIN RELAY
E
6
4
5
3
2
1
2
4
31
FRONT OXYGEN
(A/F) SENSOR
D25
B2
D31
C35
A2
A3
A33
A26
E18
REAR OXYGEN
SENSOR
T6
B47
B47
34
12
56
B134B137
B83
1
23456
B18
B262
34
12
B134A:
B135B:
B136ECM C:
B135
B83 LHD : 5
RHD : 4
LHD : 1
RHD : 1
*1
*2F2 B100
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
F2
1234 5678910 11 12 13 14 15 16 17 18 19 20567
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 3556 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
B136
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
B122
12345678
B262T6B1812341234
1
2
31
B18
T5
3
1
4
4
6
B137
D:
14RHD
RHDLHD LHD
2
B122*2*1
B18
T5
RHD
LHD
RHD
LHD

EN(H4DOTC)-188
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
AX:DTC P0458 EVAPORATIVE EMISSION CONTROL SYSTEM PURGE CON-
TROL VALVE CIRCUIT LOW
DTC DETECTING CONDITION:
Two consecutive driving cycles with fault
TROUBLE SYMPTOM:
Erroneous idling
CAUTION:
After repair or replacement of faulty parts, conduct Clear Memory Mode ERATION, Clear Memory Mode.> and Inspection Mode .
WIRING DIAGRAM:
EN-02335
MAIN RELAY
B47 1 2 3 5 4 6
BATTERY
E
B61F44
F60
: LHD
E3
F44B47
B134
B134
E4
PURGE CONTROL
SOLENOID VALVEECM
14 2 1
7LHD
RHD
LHD
RHDSBF-5123456783412
56
2 1
B200
F74
RHD
RHD
LHD LHD
B100
F2
RHD
RHD
1
5LHD LHD
: LHD
: RHD
123
4
56
78
9
1011 12
1314 15 16
B21
E4
F60
12
F74
B21
: RHD34
128910 11
12 13 14 15 16 17 18 19 20 21 22 23 2456 7
F2 : LHD
E2
: RHD
1234 5678910 11 12 13 14 15 16 17 18 19 20
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

EN(H4DOTC)-190
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
AY:DTC P0459 EVAPORATIVE EMISSION CONTROL SYSTEM PURGE CON-
TROL VALVE CIRCUIT HIGH
DTC DETECTING CONDITION:
Two consecutive driving cycles with fault
TROUBLE SYMPTOM:
Erroneous idling
CAUTION:
After repair or replacement of faulty parts, conduct Clear Memory Mode ERATION, Clear Memory Mode.> and Inspection Mode .
WIRING DIAGRAM:
EN-02335
MAIN RELAY
B47 1 2 3 5 4 6
BATTERY
E
B61F44
F60
: LHD
E3
F44B47
B134
B134
E4
PURGE CONTROL
SOLENOID VALVEECM
14 2 1
7LHD
RHD
LHD
RHDSBF-5123456783412
56
2 1
B200
F74
RHD
RHD
LHD LHD
B100
F2
RHD
RHD
1
5LHD LHD
: LHD
: RHD
123
4
56
78
9
1011 12
1314 15 16
B21
E4
F60
12
F74
B21
: RHD34
128910 11
12 13 14 15 16 17 18 19 20 21 22 23 2456 7
F2 : LHD
E2
: RHD
1234 5678910 11 12 13 14 15 16 17 18 19 20
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

EN(H4DOTC)-191
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step Check Yes No
1 CHECK OUTPUT SIGNAL FROM ECM.
1) Turn the ignition switch to OFF.
2) Connect the test mode connector at the
lower portion of instrument panel (on the
driver’s side).
3) Turn the ignition switch to ON.
4) While operating the purge control solenoid
valve, measure voltage between ECM and
chassis ground.
N
OTE:
Purge control solenoid valve operation can be
executed using Subaru Select Monitor.For the
procedure, refer to “Compulsory Valve Opera-
tion Check Mode”. Compulsory Valve Operation Check Mode.>
Connector & terminal
(B134) No. 14 (+) — Chassis ground (
−):Is the voltage 0 — 13 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.In this
case, repair poor
contact in ECM
connector.
2 CHECK OUTPUT SIGNAL FROM ECM.
1) Turn the ignition switch to ON.
2) Measure the voltage between ECM and
chassis ground.
Connector & terminal
(B134) No. 14 (+) — Chassis ground (
−):Is the voltage more than 10 V? Go to step 4.Go to step 3.
3 CHECK POOR CONTACT.
Check poor contact in ECM connector. Is there poor contact in ECM
connector?Repair the poor
contact in ECM
connector.Replace the ECM.
FU(H4DOTC)-50,
Engine Control
Module (ECM).>
4 CHECK HARNESS BETWEEN PURGE CON-
TROL SOLENOID VALVE AND ECM CON-
NECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from purge con-
trol solenoid valve.
3) Turn the ignition switch to ON.
4) Measure the voltage between ECM and
chassis ground.
Connector & terminal
(B134) No. 14 (+) — Chassis ground (
−):Is the voltage more than 10 V? Repair battery
short circuit in har-
ness between
ECM and purge
control solenoid
valve connec-
tor.After repair,
replace the ECM.
FU(H4DOTC)-50,
Engine Control
Module (ECM).>Go to step 5.
5 CHECK PURGE CONTROL SOLENOID
VALVE.
1) Turn the ignition switch to OFF.
2) Measure the resistance between purge
control solenoid valve terminals.
Te r m i n a l s
No. 1 — No. 2:Is the resistance less than 1
Ω?Replace the purge
control solenoid
valve and ECM.
EC(H4DOTC)-7,
Purge Control
Solenoid Valve.>
FU(H4DOTC)-50,
Engine Control
Module (ECM).>Go to step 6.
6 CHECK POOR CONTACT.
Check poor contact in ECM connector.Is there poor contact in ECM
connector?Repair the poor
contact in ECM
connector.Replace the ECM.
FU(H4DOTC)-50,
Engine Control
Module (ECM).>