ECU SUBARU FORESTER 2004 Service Repair Manual

EN(H4DOTC)-132
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
W: DTC P0129 BAROMETRIC PRESSURE TOO LOW
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 .
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
P0125.Go to step 2.
2 CHECK ENGINE COOLING SYSTEM.
N
OTE:
Check the following items:
 Thermostat open stuck
 Coolant level
 Coolant freeze
 Tire diameterIs there a fault in engine cool-
ing system?Replace the ther-
mostat. CO(H4SO)-26,
Thermostat.>Replace the
engine coolant
temperature sen-
sor. FU(H4DOTC)-29,
Engine Coolant
Temperature Sen-
sor.>
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:
It is not necessary
to inspect DTC
P0129.Replace the ECM.
FU(H4DOTC)-50,
Engine Control
Module (ECM).>
NOTE:
Atmospheric pres-
sure sensor is built
in ECM.

EN(H4DOTC)-137
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Z: DTC P0133 O2 SENSOR CIRCUIT SLOW RESPONSE (BANK 1 SENSOR 1)
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 .
WIRING DIAGRAM:
EN-02320
BATTERYMAIN RELAYSBF-5
B47 1 2 3 5 4 6
E
E
B100F2
14LHD
RHD
LHD
RHD
B100
F2
F60
E3
20
3
RHD
RHD6
72
3
33
26
25
ECMB134
: LHD: LHD
B21: RHD: RHD
1
4 2
3
B262
FRONT OXYGEN
(A/F) SENSOR
3412
56
123
4
56
78
9
1011 12
1314 15 16
B21
F60
B47
B262
B134
F2
LHD LHD
1234
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
1234 5678910 11 12 13 14 15 16 17 18 19 20
: LHDE2: RHD

EN(H4DOTC)-141
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
AB:DTC P0137 O2 SENSOR CIRCUIT LOW VOLTAGE (BANK 1 SENSOR 2)
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 .
WIRING DIAGRAM:
MAIN RELAY
B47 1 2 3 5 4 6
E
T5
*1
*2 B18
3
B122
1
3
T6 REAR
OXYGEN SENSOR
A6
A7D31
C35
ECMB135
B136 B :
B134 A :
C :
1
4
B83
B2 D25
B137D :
EN-02321
: LHD
: RHD34
12
56
B21
B134
B135
F60
B83
B47T6
B1361
23456
F2
2143
LHD : 5
RHD : 4
LHD : 1
RHD : 1*1
*2
BATTERY
B100F2 14LHD
RHD
LHD
RHD LHD
RHD
LHD
RHD 4
6
E
B100
F2
F60
E3
20 3
RHD
LHD
RHD
: LHD
B21: RHD
LHD
: LHDE2
: RHD
B18
B122
B137
2345 678911 12 13 14 17 18 19 201101516
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
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
12345678
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
123
4
56
78
9
1011 12
1314 15 16
1234
4
22
T5
B18
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)-144
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
AC:DTC P0138 O2 SENSOR CIRCUIT HIGH VOLTAGE (BANK 1 SENSOR 2)
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 .
WIRING DIAGRAM:
MAIN RELAY
B47 1 2 3 5 4 6
E
T5
*1
*2 B18
3
B122
1
3
T6 REAR
OXYGEN SENSOR
A6
A7D31
C35
ECMB135
B136 B :
B134 A :
C :
1
4
B83
B2 D25
B137D :
EN-02321
: LHD
: RHD34
12
56
B21
B134
B135
F60
B83
B47T6
B1361
23456
F2
2143
LHD : 5
RHD : 4
LHD : 1
RHD : 1*1
*2
BATTERY
B100F2 14LHD
RHD
LHD
RHD LHD
RHD
LHD
RHD 4
6
E
B100
F2
F60
E3
20 3
RHD
LHD
RHD
: LHD
B21: RHD
LHD
: LHDE2
: RHD
B18
B122
B137
2345 678911 12 13 14 17 18 19 201101516
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
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
12345678
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
123
4
56
78
9
1011 12
1314 15 16
1234
4
22
T5
B18
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)-147
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
AD:DTC P0139 O2 SENSOR CIRCUIT SLOW RESPONSE (BANK 1 SENSOR 2)
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 .
WIRING DIAGRAM:
MAIN RELAY
B47 1 2 3 5 4 6
E
T5
*1
*2 B18
3
B122
1
3
T6 REAR
OXYGEN SENSOR
A6
A7D31
C35
ECMB135
B136 B :
B134 A :
C :
1
4
B83
B2 D25
B137D :
EN-02321
: LHD
: RHD34
12
56
B21
B134
B135
F60
B83
B47T6
B1361
23456
F2
2143
LHD : 5
RHD : 4
LHD : 1
RHD : 1*1
*2
BATTERY
B100F2 14LHD
RHD
LHD
RHD LHD
RHD
LHD
RHD 4
6
E
B100
F2
F60
E3
20 3
RHD
LHD
RHD
: LHD
B21: RHD
LHD
: LHDE2
: RHD
B18
B122
B137
2345 678911 12 13 14 17 18 19 201101516
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
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
12345678
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
123
4
56
78
9
1011 12
1314 15 16
1234
4
22
T5
B18
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)-149
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
AF:DTC P0172 SYSTEM TOO RICH (BANK 1)
DTC DETECTING CONDITION:
Two consecutive driving cycles with fault
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 .
Step Check Yes No
1 CHECK EXHAUST SYSTEM.Are there holes or looseness of
the bolts on exhaust system?Repair exhaust
system.Go to step 2.
2 CHECK AIR INTAKE SYSTEM.Are there holes, loose bolts or
disconnection of hose on air
intake system?Repair air intake
system.Go to step 3.
3 CHECK FUEL PRESSURE.
Warning:
 Place “NO FIRE” signs near the working
area.
 Be careful not to spill fuel.
1) Release the fuel pressure.
(1) Disconnect the connector from fuel
pump relay.
(2) Start the engine and run it until it stalls.
(3) After the engine stalls, crank it for five
more seconds.
(4) Turn the ignition switch to OFF.
2) Connect the connector to fuel pump relay.
3) Disconnect the fuel delivery hose from fuel
filter, and connect the fuel pressure gauge.
4) Install the fuel filler cap.
5) Start the engine and idle while gear posi-
tion is neutral.
6) Measure the fuel pressure while discon-
necting pressure regulator vacuum hose from
intake manifold.
Warning:
Release fuel pressure before removing the
fuel pressure gauge.
N
OTE:
If fuel pressure does not increase, squeeze the
fuel return hose 2 to 3 times, then measure fuel
pressure again.Is measured value 284 — 314
kPa (2.9 — 3.2 kg/cm
2, 41 —
46 psi)?Go to step 4.Repair the follow-
ing items.
Fuel pressure is
too high:
 Clogged fuel
return line or
bent hose
Fuel pressure is
too low:
 Improper fuel
pump discharge
 Clogged fuel
supply line

EN(H4DOTC)-163
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
AN:DTC P0304 CYLINDER 4 MISFIRE DETECTED
DTC DETECTING CONDITION:
 Two consecutive driving cycles with fault
 Immediately at fault recognition (A misfire which could damage catalyst occurs.)
TROUBLE SYMPTOM:
 Engine stalls.
 Erroneous idling
 Rough driving
CAUTION:
After repair or replacement of faulty parts, conduct Clear Memory Mode ERATION, Clear Memory Mode.> and Inspection Mode .

EN(H4DOTC)-170
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step Check Yes No
1 CHECK HARNESS BETWEEN KNOCK SEN-
SOR AND ECM CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Measure the resistance between ECM har-
ness connector and chassis ground.
Connector & terminal
(B136) No. 25 — Chassis ground:Is the resistance more than
700 kΩ?Go to step 2.Repair the har-
ness and connec-
tor.
N
OTE:
In this case repair
the following:
 Open circuit in
harness between
knock sensor and
ECM connector
 Poor contact in
knock sensor con-
nector
 Poor contact in
coupling connector
2 CHECK KNOCK SENSOR.
1) Disconnect the connector from knock sen-
sor.
2) Measure the resistance between knock
sensor connector terminal and engine ground.
Te r m i n a l s
No. 2 — Engine ground:Is the resistance more than
700 kΩ?Go to step 3.Repair the har-
ness and connec-
tor.
N
OTE:
In this case repair
the following:
 Poor contact in
knock sensor con-
nector
 Poor contact in
coupling connector
3 CHECK CONDITION OF KNOCK SENSOR
INSTALLATION.Is the knock sensor installation
bolt tightened securely?Replace the knock
sensor. FU(H4DOTC)-33,
Knock Sensor.>Tighten knock sen-
sor installation bolt
securely.

EN(H4DOTC)-174
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step Check Yes No
1 CHECK HARNESS BETWEEN CRANK-
SHAFT POSITION SENSOR AND ECM CON-
NECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from the crank-
shaft position sensor.
3) Measure the resistance of harness
between crankshaft position sensor connector
and engine ground.
Connector & terminal
(E10) 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
crankshaft posi-
tion sensor and
ECM connector
 Poor contact in
ECM connector.
 Poor contact in
coupling connectorGo to step 2.
2 CHECK HARNESS BETWEEN CRANK-
SHAFT POSITION SENSOR AND ECM CON-
NECTOR.
Measure the resistance of harness between
crankshaft position sensor connector and
engine ground.
Connector & terminal
(E10) No. 1 — Engine ground:Is the resistance more than 1
MΩ?Go to step 3.Repair ground
short circuit in har-
ness between
crankshaft posi-
tion sensor and
ECM connector.
N
OTE:
The harness be-
tween both con-
nectors are
shielded.Repair
ground short circuit
in harness togeth-
er with shield.
3 CHECK HARNESS BETWEEN CRANK-
SHAFT POSITION SENSOR AND ECM CON-
NECTOR.
Measure the resistance of harness between
crankshaft position sensor connector and
engine ground.
Connector & terminal
(E10) No. 2 — Engine ground:Is the resistance less than 5
Ω?Go to step 4.Repair the har-
ness and connec-
tor.
NOTE:
In this case repair
the following:
 Open circuit in
harness between
crankshaft posi-
tion sensor and
ECM connector
 Poor contact in
ECM connector.
 Poor contact in
coupling connector
4 CHECK CONDITION OF CRANKSHAFT PO-
SITION SENSOR.Is the crankshaft position sen-
sor installation bolt tightened
securely?Go to step 5.Tighten the crank-
shaft position sen-
sor installation bolt
securely.
5 CHECK CRANKSHAFT POSITION SENSOR.
1) Remove the crankshaft position sensor.
2) Measure the resistance between connector
terminals of crankshaft position sensor.
Te r m i n a l s
No. 1 — No. 2:Is the resistance 1 — 4 kΩ? Repair poor con-
tact in crankshaft
position sensor
connector.Replace the crank-
shaft position sen-
sor. FU(H4DOTC)-30,
Crankshaft Posi-
tion Sensor.>

EN(H4DOTC)-175
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
AR:DTC P0336 CRANKSHAFT POSITION SENSOR “A” CIRCUIT RANGE/PER-
FORMANCE
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-02330
2
1E1
E10
B20
CRANKSHAFT
POSITION
SENSOR
2
1
B135 ECM
22
31 10
E
E10
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