SUBARU FORESTER 2004 Service Repair Manual

EN(H4DOTC 2.5)-237
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step Check Yes No
1 CHECK ACCELERATOR PEDAL POSITION
SENSOR OUTPUT.
1) Turn the ignition switch to ON.
2) Measure the voltage between ECM con-
nector terminals.
Connector & terminal
(B136) No. 17 (+) — (B136) No. 34 (
−):
3) Check the voltage change by shaking the
harness and connector of ECM and accelera-
tor pedal position sensor connector and har-
ness.Is the voltage more than 0.4 V? Go to step 2.Go to step 3.
2 CHECK POOR CONTACT.
Check poor contact in connector between
ECM and accelerator pedal position sensor.Is there poor contact? Repair the poor
contact.Temporary poor
contact occurred,
but it is normal at
present.
3 CHECK HARNESS BETWEEN ECM AND AC-
CELERATOR PEDAL POSITION SENSOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Disconnect the connector from the acceler-
ator pedal position sensor.
4) Measure the resistance between ECM con-
nector and accelerator pedal position sensor
connector.
Connector & terminal
(B136) No. 15 — (B315) No. 3:
(B136) No. 17 — (B315) No. 5:Is the resistance less than 1
Ω?Go to step 4.Repair the open
circuit of harness
connector.
4 CHECK HARNESS BETWEEN ECM AND AC-
CELERATOR PEDAL POSITION SENSOR.
Measure the resistance between ECM connec-
tor and chassis ground.
Connector & terminal
(B136) No. 15 — Chassis ground:
(B136) No. 17 — Chassis ground:Is the resistance more than 1
MΩ?Go to step 5.Repair the chas-
sis short circuit of
harness.
5 CHECK POWER SUPPLY OF ACCELERA-
TOR PEDAL POSITION SENSOR.
1) Connect the ECM connector.
2) Turn the ignition switch to ON.
3) Measure the voltage between accelerator
pedal position sensor connector and engine
ground.
Connector & terminal
(B315) No. 3 (+) — Engine ground (
−):
4) Check the voltage change by shaking the
harness and connector of ECM while monitor-
ing the value with voltage meter.Is the voltage 4.5 — 5.5 V? Go to step 6.Repair the poor
contact in ECM
connector. Replace
the ECM if defec-
tive. <Ref. to
FU(H4DOTC 2.5)-
41, Engine Con-
trol Module
(ECM).>
6 CHECK ACCELERATOR PEDAL POSITION
SENSOR.
Measure the resistance of accelerator pedal
position sensor.
Te r m i n a l s
No. 3 — No. 4:Is the resistance 1.2 — 4.8
kΩ?Go to step 7.Replace the accel-
erator pedal posi-
tion sensor.

EN(H4DOTC 2.5)-238
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
7 CHECK ACCELERATOR PEDAL POSITION
SENSOR.
Measure the resistance of accelerator pedal
position sensor.
Te r m i n a l s
No. 5 — No. 4:
Check the measured value is within the specifi-
cation without depressing the accelerator pedal.Is the resistance 0.2 — 1.0
kΩ?Go to step 8.Replace the accel-
erator pedal posi-
tion sensor.
8 CHECK ACCELERATOR PEDAL POSITION
SENSOR.
Measure the resistance of accelerator pedal
position sensor.
Te r m i n a l s
No. 5 — No. 4:
Check the measured value is within the specifi-
cation with the accelerator pedal depressed.Is the resistance 0.5 — 2.5
kΩ?Repair the poor
contact in ECM
connector.
Replace the ECM
if defective.Replace the accel-
erator pedal posi-
tion sensor. Step Check Yes No

EN(H4DOTC 2.5)-239
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
CC:DTC P2123 THROTTLE/PEDAL POSITION SENSOR/SWITCH “D” 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 <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-02377
B315B83
B21
E
C:ECM
B136
B137
D:
C:B136
B137
D:
B122
B21
E2
B315
1
3
354126 C15
C17
C34
C16
C28
C35
D1D2
16
123
4
56
78
9
1011 12
1314 15 16
123456
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
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
MAINSUB
ACCELERATOR
PEDAL
POSITION
SENSOR
B833
112345678

EN(H4DOTC 2.5)-240
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step Check Yes No
1 CHECK ACCELERATOR PEDAL POSITION
SENSOR OUTPUT.
1) Turn the ignition switch to ON.
2) Read the data of main accelerator pedal
position sensor signal using Subaru Select
Monitor.
3) Check the voltage change by shaking the
harness and connector of ECM, engine har-
ness connector and accelerator pedal position
sensor connector harness.Is the voltage less than 4.8 V? Go to step 2.Go to step 3.
2 CHECK POOR CONTACT.
Check poor contact in connector between
ECM and accelerator pedal position sensor.Is there poor contact? Repair the poor
contact.Temporary poor
contact occurred,
but it is normal at
present.
3 CHECK HARNESS BETWEEN ECM AND AC-
CELERATOR PEDAL POSITION SENSOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Disconnect the connector from the acceler-
ator pedal position sensor.
4) Measure the resistance between ECM con-
nector and accelerator pedal position sensor con-
nector.
Connector & terminal
(B136) No. 34 — (B315) No. 4:Is the resistance less than 1
Ω?Go to step 4.Repair the open
circuit of harness
connector.
4 CHECK HARNESS BETWEEN ECM AND AC-
CELERATOR PEDAL POSITION SENSOR.
1) Connect the ECM connector.
2) Measure the resistance between accelerator
pedal position sensor connector and engine
ground.
Connector & terminal
(B315) No. 4 — Engine ground:Is the resistance less than 5
Ω?Go to step 5.Repair the poor
contact in ECM
connector.
Replace the ECM
if defective.
5 CHECK HARNESS BETWEEN ECM AND AC-
CELERATOR PEDAL POSITION SENSOR.
1) Connect the ECM connector.
2) Turn the ignition switch to ON.
3) Measure the voltage between accelerator
pedal position sensor connector and engine
ground.
Connector & terminal
(B315) No. 3 (+) — Engine ground (
−):
4) Check the voltage is above the specified
value when shaking the harness and connec-
tor of ECM while monitoring the value with volt-
age meter.Is the voltage more than 6 V? Go to step 6.Repair battery
short circuit in har-
ness between
ECM connector
and accelerator
pedal position sen-
sor connector.
6 CHECK POWER SUPPLY OF ACCELERA-
TOR PEDAL POSITION SENSOR.
1) Measure the voltage between accelerator
pedal position sensor connector and engine
ground.
Connector & terminal
(B315) No. 5 (+) — Engine ground (
−):
2) Check the voltage is below the specified
value when shaking the harness and connec-
tor of ECM while monitoring the value with volt-
age meter.Is the voltage less than 4.8 V? Go to step 7.Repair short circuit
in harness between
ECM connector and
accelerator pedal
position sensor con-
nector.

EN(H4DOTC 2.5)-241
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
7 CHECK HARNESS BETWEEN ECM AND AC-
CELERATOR PEDAL POSITION SENSOR.
1) Turn the ignition switch to OFF.
2) Connect the accelerator pedal position sen-
sor connector.
3) Turn the ignition switch to ON.
4) Measure the voltage between ECM connector
and chassis ground.
Connector & terminal
(B136) No. 17 (+) — Chassis ground (
−):Is the voltage 4.8 V? Repair the poor
contact in ECM
connector.
Replace the ECM
if defective.Repair poor con-
tact in accelerator
pedal position sen-
sor connector.
Replace the accel-
erator pedal posi-
tion sensor if
defective. Step Check Yes No

EN(H4DOTC 2.5)-242
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
CD:DTC P2127 THROTTLE/PEDAL POSITION SENSOR/SWITCH “E” 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 <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-02377
B315B83
B21
E
C:ECM
B136
B137
D:
C:B136
B137
D:
B122
B21
E2
B315
1
3
354126 C15
C17
C34
C16
C28
C35
D1D2
16
123
4
56
78
9
1011 12
1314 15 16
123456
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
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
MAINSUB
ACCELERATOR
PEDAL
POSITION
SENSOR
B833
112345678

EN(H4DOTC 2.5)-243
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step Check Yes No
1 CHECK ACCELERATOR PEDAL POSITION
SENSOR OUTPUT.
1) Turn the ignition switch to ON.
2) Measure the voltage between ECM con-
nector terminals.
Connector & terminal
(B136) No. 28 (+) — (B136) No. 35 (
−):
3) Check the voltage exceed the standard
value by shaking the harness and connector of
ECM and accelerator pedal position sensor
connector and harness.Is the voltage more than 0.4 V? Go to step 2.Go to step 3.
2 CHECK POOR CONTACT.
Check poor contact in connector between
ECM and accelerator pedal position sensor.Is there poor contact? Repair the poor
contact.Temporary poor
contact occurred,
but it is normal at
present.
3 CHECK HARNESS BETWEEN ECM AND AC-
CELERATOR PEDAL POSITION SENSOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Disconnect the connector from the acceler-
ator pedal position sensor.
4) Measure the resistance between ECM con-
nector and accelerator pedal position sensor con-
nector.
Connector & terminal
(B136) No. 16 — (B315) No. 1:
(B136) No. 28 — (B315) No. 2:Is the resistance less than 1
Ω?Go to step 4.Repair the open
circuit of harness
connector.
4 CHECK HARNESS BETWEEN ECM AND AC-
CELERATOR PEDAL POSITION SENSOR.
Measure the resistance between ECM connec-
tor and chassis ground.
Connector & terminal
(B136) No. 16 — Chassis ground:
(B136) No. 28 — Chassis ground:Is the resistance more than 1
MΩ?Go to step 5.Repair the chas-
sis short circuit of
harness.
5 CHECK POWER SUPPLY OF ACCELERA-
TOR PEDAL POSITION SENSOR.
1) Connect the ECM connector.
2) Turn the ignition switch to ON.
3) Measure the voltage between accelerator
pedal position sensor connector and engine
ground.
Connector & terminal
(B315) No. 1 (+) — Engine ground (
−):
4) Check the voltage is within the specified
value when shaking the harness and connector
of ECM while monitoring the value with voltage
meter.Is the voltage 4.5 — 5.5 V? Go to step 6.Repair the poor
contact in ECM
connector.
Replace the ECM
if defective.
6 CHECK ACCELERATOR PEDAL POSITION
SENSOR.
Measure the resistance of accelerator pedal
position sensor.
Te r m i n a l s
No. 1 — No. 6:Is the resistance 0.75 — 3.15
kΩ?Go to step 7.Replace the accel-
erator pedal posi-
tion sensor.

EN(H4DOTC 2.5)-244
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
7 CHECK ACCELERATOR PEDAL POSITION
SENSOR.
1) Measure the resistance of accelerator
pedal position sensor.
Te r m i n a l s
No. 2 — No. 6:
2) Check the measured value is within the
specification without depressing the accelera-
tor pedal.Is the resistance 0.15 — 0.63
kΩ?Go to step 8.Replace the accel-
erator pedal posi-
tion sensor.
8 CHECK ACCELERATOR PEDAL POSITION
SENSOR.
1) Measure the resistance of accelerator
pedal position sensor.
Te r m i n a l s
No. 2 — No. 6:
2) Check the measured value is within the
specification with the accelerator pedal
depressed.Is the resistance 0.28 — 1.68
kΩ?Repair the poor
contact in ECM
connector.
Replace the ECM
if defective.Replace the accel-
erator pedal posi-
tion sensor. Step Check Yes No

EN(H4DOTC 2.5)-245
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
CE:DTC P2128 THROTTLE/PEDAL POSITION SENSOR/SWITCH “E” 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 <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-02377
B315B83
B21
E
C:ECM
B136
B137
D:
C:B136
B137
D:
B122
B21
E2
B315
1
3
354126 C15
C17
C34
C16
C28
C35
D1D2
16
123
4
56
78
9
1011 12
1314 15 16
123456
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
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
MAINSUB
ACCELERATOR
PEDAL
POSITION
SENSOR
B833
112345678

EN(H4DOTC 2.5)-246
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step Check Yes No
1 CHECK ACCELERATOR PEDAL POSITION
SENSOR OUTPUT.
1) Turn the ignition switch to ON.
2) Read the data of sub accelerator pedal
position sensor signal using Subaru Select
Monitor.
3) Check the voltage change by shaking the
harness and connector of ECM, engine har-
ness connector and accelerator pedal position
sensor connector harness.Is the voltage less than 4.8 V? Go to step 2.Go to step 3.
2 CHECK POOR CONTACT.
Check poor contact in connector between
ECM and accelerator pedal position sensor.Is there poor contact? Repair the poor
contact.Temporary poor
contact occurred,
but it is normal at
present.
3 CHECK HARNESS BETWEEN ECM AND AC-
CELERATOR PEDAL POSITION SENSOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Disconnect the connector from the acceler-
ator pedal position sensor.
4) Measure the resistance between ECM con-
nector and accelerator pedal position sensor con-
nector.
Connector & terminal
(B136) No. 35 — (B315) No. 6:Is the resistance less than 1
Ω?Go to step 4.Repair the open
circuit of harness
connector.
4 CHECK HARNESS BETWEEN ECM AND AC-
CELERATOR PEDAL POSITION SENSOR.
1) Connect the ECM connector.
2) Measure the resistance between accelerator
pedal position sensor connector and engine
ground.
Connector & terminal
(B315) No. 6 — Engine ground:Is the resistance less than 5
Ω?Go to step 5.Repair the poor
contact in ECM
connector.
Replace the ECM
if defective.
5 CHECK HARNESS BETWEEN ECM AND AC-
CELERATOR PEDAL POSITION SENSOR.
1) Connect the ECM connector.
2) Turn the ignition switch to ON.
3) Measure the voltage between accelerator
pedal position sensor connector and engine
ground.
Connector & terminal
(B315) No. 1 (+) — Engine ground (
−):
4) Check the voltage is above the specified value
when shaking the harness and connector of ECM
while monitoring the value with voltage meter.Is the voltage less than 6 V? Go to step 6.Repair battery short
circuit in harness
between ECM con-
nector and acceler-
ator pedal position
sensor connector.
6 CHECK POWER SUPPLY OF ACCELERA-
TOR PEDAL POSITION SENSOR.
1) Measure the voltage between accelerator
pedal position sensor connector and engine
ground.
Connector & terminal
(B315) No. 2 (+) — Engine ground (
−):
2) Check the voltage change by shaking the
harness and connector of ECM while monitor-
ing the value with voltage meter.Is the voltage less than 4.8 V? Go to step 7.Repair short circuit
in harness between
ECM connector and
accelerator pedal
position sensor con-
nector.