2004 SUBARU FORESTER check engine

EN(H4DOTC 2.5)-230
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
27 CHECK ELECTRONIC THROTTLE CON-
TROL GROUND CIRCUIT.
Measure the resistance between ECM connec-
tor and engine ground.
Connector & terminal
(B137) No. 3 — Engine ground:Is the resistance less than 10
Ω?Go to step 28.Repair the open
circuit of harness.
28 CHECK ELECTRONIC THROTTLE CON-
TROL.
Measure the resistance between electronic
throttle control terminals.
Te r m i n a l s
No. 1 — No. 2:Is the resistance less than 5
Ω?Go to step 29.Repair the elec-
tronic throttle con-
trol.
29 CHECK ELECTRONIC THROTTLE CON-
TROL.
Move the throttle valve to the fully open and
fully closed positions with fingers
Check the valve returns to the specified posi-
tion when releasing fingers.Does the valve return to the
specified position?
Standard value: 3 mm (0.12 in)
from fully closed positionRepair the poor
contact in ECM
connector. Replace
the ECM if defec-
tive. FU(H4DOTC 2.5)-
41, Engine Con-
trol Module
(ECM).>Repair the elec-
tronic throttle con-
trol. Step Check Yes No

EN(H4DOTC 2.5)-233
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step Check Yes No
1 CHECK ELECTRONIC THROTTLE CON-
TROL RELAY.
1) Turn the ignition switch to OFF.
2) Remove the electronic throttle control relay.
3) Connect the battery to electronic throttle
control relay terminals No. 1 and No. 3.
4) Measure the resistance between electronic
throttle control terminals.
Te r m i n a l s
(B309) No. 2 — (B309) No. 4:Is the resistance less than 1
Ω?Go to step 2.Replace the elec-
tronic throttle con-
trol relay.
2 CHECK POWER SUPPLY OF ELECTRONIC
THROTTLE CONTROL RELAY.
Measure the voltage between electronic throt-
tle control relay connector and engine ground.
Connector & terminal
(B309) No. 1 (+) — Engine ground (
−):
(B309) No. 2 (+) — Engine ground (
−):Is the voltage more than 5 V? Go to step 3.Repair open or
ground short cir-
cuit of power sup-
ply circuit.
3 CHECK HARNESS BETWEEN ECM AND
ELECTRONIC THROTTLE CONTROL RE-
LAY.
1) Disconnect the connector from ECM.
2) Turn the ignition switch to ON.
3) Measure the voltage between electronic
throttle control relay connector and engine
ground.
Connector & terminal
(B309) No. 3 (+) — Engine ground (
−):Is the voltage less than 5 V? Go to step 4.Repair power sup-
ply short circuit in
harness between
ECM and elec-
tronic throttle con-
trol relay.
4 CHECK HARNESS BETWEEN ECM AND
ELECTRONIC THROTTLE CONTROL RE-
LAY.
1) Turn the ignition switch to OFF.
2) Measure the resistance between electronic
throttle control relay connector and chassis
ground.
Connector & terminal
(B309) No. 3 — Engine ground:
(B309) No. 4 — Engine ground:Is the resistance more than 1
MΩ?Go to step 5.Repair ground
short circuit in har-
ness between
ECM and elec-
tronic throttle con-
trol relay.
5 CHECK HARNESS BETWEEN ECM AND
ELECTRONIC THROTTLE CONTROL RE-
LAY.
Measure the resistance between ECM connector
and electronic throttle control relay connector.
Connector & terminal
(B135) No. 35 — (B309) No. 3:
(B137) No. 6 — (B309) No. 4:Is the resistance less than 1
Ω?Repair the poor
contact in ECM con-
nector. Replace the
ECM if defective.Repair open circuit
in harness between
ECM and electronic
throttle control relay.

EN(H4DOTC 2.5)-235
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
CA:DTC P2109 THROTTLE/PEDAL POSITION SENSOR A MINIMUM STOP PER-
FORMANCE
NOTE:
For diagnostic procedure, refer to DTC P2101. TUATOR CONTROL MOTOR CIRCUIT RANGE/PERFORMANCE, Diagnostic Procedure with Diagnostic
Trouble Code (DTC).>
Step Check Yes No
1 CHECK ELECTRONIC THROTTLE CON-
TROL RELAY.
1) Turn the ignition switch to OFF.
2) Remove the electronic throttle control relay.
3) Measure the resistance between electronic
throttle control relay terminals.
Te r m i n a l s
No. 2 — No. 4:Is the resistance more than 1
MΩ?Go to step 2.Replace the elec-
tronic throttle con-
trol relay.
2 CHECK POWER SUPPLY SHORT CIRCUIT
OF ELECTRONIC THROTTLE CONTROL
RELAY.
1) Turn the ignition switch to ON.
2) Measure the voltage between electronic
throttle control relay connector and engine
ground.
Connector & terminal
(B309) No. 4 (+) — Engine ground (
−):Is the voltage more than 5 V? Go to step 3.Repair power sup-
ply short circuit in
harness between
ECM and elec-
tronic throttle con-
trol relay.
3 CHECK HARNESS BETWEEN ECM AND
ELECTRONIC THROTTLE CONTROL RE-
LAY.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Measure the resistance between ECM con-
nector and engine ground.
Connector & terminal
(B135) No. 35 — Engine ground:Is the resistance more than 1
MΩ?Repair the poor
contact in ECM
connector.
Replace the ECM
if defective.Repair ground
short circuit in har-
ness between
ECM and elec-
tronic throttle con-
trol relay.

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. 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)-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)-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.