ECU SUBARU FORESTER 2004 Service Repair Manual

EN(H4DOTC)-7
ENGINE (DIAGNOSTIC)
General Description
12) Observe the following cautions when installing
a radio in MFI equipped models.
CAUTION:
 The antenna must be kept as far apart as pos-
sible from the control unit. (The ECM is located
under the steering column, inside of the instru-
ment panel lower trim panel.)
 The antenna feeder must be placed as far
apart as possible from the ECM and MFI har-
ness.
 Carefully adjust the antenna for correct
matching.
 When mounting a large power type radio, pay
special attention to the three items above men-
tioned.
 Incorrect installation of the radio may affect
the operation of the ECM.
13) Before disconnecting the fuel hose, disconnect
the fuel pump connector and crank the engine for
more than five seconds to release pressure in the
fuel system.If engine starts during this operation,
run it until it stops.
14) Problems in the electronic-controlled automatic
transmission may be caused by failure of the en-
gine, the electronic control system, the transmis-
sion proper, or by a combination of these.These
three causes (engine, electronic control system,
transmission) must be distinguished clearly when
performing diagnostics.
15) Diagnostics should be conducted by rotating
with simple, easy operations and proceeding to
complicated, difficult operations.The most impor-
tant thing in diagnostics is to understand the cus-
tomer’s complaint, and distinguish between the
three causes.
16) On the model with ABS, when performing driv-
ing test in jacked-up or lifted-up position, some-
times the warning light may be lit, but this is not a
malfunction of the system.The reason for this is the
speed difference between the front and rear
wheels.After diagnosis of engine control system,
perform the ABS memory clearance procedure of
self-diagnosis function.
B: INSPECTION
Before performing diagnostics, check the following
items which might affect engine problems:
1. BATTERY
1) Measure battery voltage and specific gravity of
electrolyte.
Standard voltage: 12 V
Specific gravity: Above 1.2602) Check the condition of the main and other fuses,
and harnesses and connectors.Also check for
proper grounding.
2. ENGINE GROUND
Make sure the engine ground terminal is properly
connected to the engine.
C: NOTE
1. GENERAL DESCRIPTION
 On-board diagnosis (OBD) system detects and
indicates a fault in various inputs and outputs of the
complex electronic control.Malfunction indicator
light in the combination meter indicates occurrence
of a fault or trouble.
 Further, against such a failure or sensors as may
disable the drive, the fail-safe function is provided
to ensure the minimal driveability.
 The OBD system incorporated with the vehicles
within this engine family complies with Section
1968.1, California Code of Regulations (OBD-II
regulation).The OBD system monitors the compo-
nents and the system malfunction listed in Engine
Section which affects on emissions.
 When the system decides that a malfunction oc-
curs, malfunction indicator light illuminates.At the
same time of the malfunction indicator light illumi-
nation or blinking, the DTC and a freeze frame en-
gine conditions are stored into on-board computer.
 The OBD system stores freeze frame engine
condition data (engine load, engine coolant tem-
perature, fuel trim, engine speed and vehicle
speed, etc.) into on-board computer when it detects
a malfunction first.
 If the OBD system detects the various malfunc-
tions including the fault of fuel trim or misfire, the
OBD system first stores freeze frame engine condi-
tions about the fuel trim or misfire.
 When the malfunction does not occur again for
three consecutive driving cycles, malfunction indi-
cator light is turned off, but DTC remains at on-
board computer.
 The OBD-II system is capable of communication
with a general scan tool (OBD-II general scan tool)
formed by ISO 9141 CARB.
EN-00070

EN(H4DOTC)-42
ENGINE (DIAGNOSTIC)
Inspection Mode
1. PREPARATION FOR THE INSPECTION
MODE
1) Check battery voltage is more than 12 V and fuel
remains half [20 to 402 (5.3 to 10.6 US gal, 4.4 to
8.8 Imp gal)].
2) Lift-up the vehicle using a garage jack and place
it on rigid racks or drive the vehicle onto free rollers.
WARNING:
 Before raising the vehicle, ensure parking
brakes are applied.
 Do not use a pantograph jack in place of a rig-
id rack.
 Secure a rope or wire to the front or rear tow-
ing hooks to prevent the lateral runout of front
wheels.
 Do not abruptly depress/release clutch pedal
or accelerator pedal during works even when
the engine is operating at low speeds since this
may cause vehicle to jump off free rollers.
 In order to prevent the vehicle from slipping
due to vibration, do not place any wooden
blocks or similar items between the rigid racks
and the vehicle.
 Since the rear wheels will also rotate, do not
place anything near them.Also, make sure that
nobody goes in front of the vehicle.
2. SUBARU SELECT MONITOR
1) After clearing the memory, check for any remain-
ing unresolved trouble data. EN(H4DOTC)-47, Clear Memory Mode.>
2) Idle the engine.
3) Prepare the Subaru Select Monitor kit. EN(H4DOTC)-8, PREPARATION TOOL, General
Description.>
4) Connect the diagnosis cable to Subaru Select
Monitor.
5) Insert the cartridge to Subaru Select Monitor.
General Description.>
6) Connect the test mode connector (A) located at
the lower portion of instrument panel (on the driv-
er’s side).
(A) Rigid rack
(B) Free rollers
EN-00041
(A)
(B)
(A) Test mode connector
EN-00038
EN-00039
EN-00333
(A)

EN(H4DOTC)-70
ENGINE (DIAGNOSTIC)
Diagnostics for Engine Starting Failure
RHD model
Step Check Yes No
1 CHECK OPERATING SOUND OF FUEL
PUMP.
Make sure that fuel pump is in operation for
two seconds when turning the ignition switch to
ON.
NOTE:
Fuel pump operation check can also be execut-
ed using Subaru Select Monitor.
For the procedure, refer to “Compulsory Valve
Operation Check Mode”. EN(H4DOTC)-48, Compulsory Valve Opera-
tion Check Mode.>Does the fuel pump produce
operating sound?Check the fuel
injector circuit.
EN(H4DOTC)-71,
FUEL INJECTOR
CIRCUIT, Diag-
nostics for Engine
Starting Failure.>Display DTC.
EN(H4DOTC)-39,
OPERATION,
Read Diagnostic
Trouble Code
(DTC).>
EN-02317
B97
B135B137
R122
EE
M
10 7
6
FUEL PUMP
RELAY
FUEL PUMP
CONTROL MODULE
FUEL
PUMP
SBF-5
B46
R122
B135 B :
B137 D :
R15
R57
R58
R2
ECM
B98
B98R58
B97
R1
BATTERY
8
1
4
D28
B27
123456783412123456789102356
24
1
4
9
85
14
14
15
219
32
1234
5610 11 12 13 14 15716
23 3019 20
22 26 27 28 29817
24 3118
25
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 35567
82 1
94 310
22 23 11 12 13 14 15
24 25
2616 17
18 19 20 21
27 28 29 30 31
B46R15

EN(H4DOTC)-82
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
C: DTC P0031 HO2S HEATER CONTROL CIRCUIT LOW (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)-94
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
H: DTC P0068 MANIFOLD PRESSURE SENSOR RANGE/PERFORMANCE
DTC DETECTING CONDITION:
Two consecutive driving cycles with fault
TROUBLE SYMPTOM:
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:
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)-96
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step Check Yes No
1 CHECK IDLE SWITCH SIGNAL.
1) Turn the ignition switch to ON.
2) Operate the LED operation mode for
engine using Subaru Select Monitor.
N
OTE:
 Subaru Select Monitor
For detailed operation procedure, refer to the
“LED OPERATION MODE FOR ENGINE”.
itor.>Does the LED of {Idle Switch
Signal} come on?Go to step 2.Check the throttle
position sensor cir-
cuit. EN(H4DOTC)-
122, DTC P0121
THROTTLE/
PEDAL POSI-
TION SENSOR/
SWITCH “A” CIR-
CUIT RANGE/
PERFORMANCE,
Diagnostic Proce-
dure with Diagnos-
tic Trouble Code
(DTC).>
N
OTE:
In this case, it is
not necessary to
inspect DTC
P0106.
2 CHECK ANY OTHER DTC ON DISPLAY.Is any other DTC displayed? Check related
DTC.“List of Diag-
nostic Trouble
Code (DTC)” to EN(H4DOTC)-
74, List of Diag-
nostic Trouble
Code (DTC).>
NOTE:
In this case, it is
not necessary to
inspect DTC
P0106.Go to step 3.
3 CHECK MANIFOLD ABSOLUTE PRESSURE
SENSOR CONDITION.Is the manifold absolute pres-
sure sensor installation bolt
tightened securely?Go to step 4.Tighten manifold
absolute pressure
sensor installation
bolt securely.
4 CHECK CONDITION OF THROTTLE BODY.Is the throttle body installation
bolt tightened securely?Replace the mani-
fold absolute pres-
sure sensor. to FU(H4DOTC)-
36, Manifold Abso-
lute Pressure Sen-
sor.>Tighten throttle
body installation
bolt securely.

EN(H4DOTC)-97
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
I: DTC P0101 MASS OR VOLUME AIR FLOW CIRCUIT RANGE/PERFOR-
MANCE
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 .
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)-110
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
N: DTC P0111 INTAKE AIR TEMPERATURE CIRCUIT RANGE/PERFORMANCE
DTC DETECTING CONDITION:
Two consecutive driving cycles with fault
TROUBLE SYMPTOM:
 Erroneous idling
 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)-122
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
S: DTC P0121 THROTTLE/PEDAL POSITION SENSOR/SWITCH “A” CIRCUIT
RANGE/PERFORMANCE
DTC DETECTING CONDITION:
Two consecutive driving cycles with fault
TROUBLE SYMPTOM:
 Erroneous idling
 Engine stalls.
 Poor driving performance
 Fuel is cut.
CAUTION:
After repair or replacement of faulty parts, conduct Clear Memory Mode ERATION, Clear Memory Mode.> and Inspection Mode .
WIRING DIAGRAM:
LHD model
EN-02326
E2
E13
F61
F74
B200
B122 THROTTLE
POSITION
SENSOR
1
32
20
1918
1 2
B136 ECM
16
35 18
B136
E13
123
F61
125678
131415169101112
34
17181920
B122
F2
F2
B100
F74
12345678
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
1234 5678910 11 12 13 14 15 16 17 18 19 20
723
16

EN(H4DOTC)-131
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
V: DTC P0125 INSUFFICIENT COOLANT TEMPERATURE FOR CLOSED LOOP
FUEL CONTROL
DTC DETECTING CONDITION:
Two consecutive driving cycles with fault
TROUBLE SYMPTOM:
Engine would not return to idling.
CAUTION:
After repair or replacement of faulty parts, conduct Clear Memory Mode ERATION, Clear Memory Mode.> and Inspection Mode .
WIRING DIAGRAM:
EN-02325
B122
B136 ECM
35 14
E8 ENGINE
COOLANT
TEMPERATURE
SENSOR2
1
1 2
17
18
22
16F74
B200
LHD
LHD
RHD
RHD
LHD LHD
RHD
RHD
E8
12
3
B136
125678
131415169101112
34
17181920
B122B22 : RHD
F61 : LHD
F61
E2
: LHD
B22: RHD
F74
34
12 8910 11
12 13 14 15 16 17 18 19 20 21 22 23 2456 7
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
: LHDE3: RHD