Subaru Legacy 2004 Service Manual page 639

Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step
1 CHECK ACCELERATOR POSITION SEN-
SOR OUTPUT.
1) Turn the ignition switch to ON.
2) Read the data of main accelerator position
sensor signal using Subaru Select Monitor.
2 CHECK POOR CONTACT.
Check poor contact in connector between
ECM and accelerator position sensor.
3 CHECK HARNESS BETWEEN ECM AND AC-
CELERATOR POSITION SENSOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Disconnect the connector from accelerator
position sensor.
4) Measure the resistance between ECM con-
nector and accelerator position sensor connec-
tor.
Connector & terminal
(B137) No. 29 — (B315) No. 5:
(B137) No. 25 — (B315) No. 3:
4 CHECK HARNESS BETWEEN ECM AND AC-
CELERATOR POSITION SENSOR.
Measure the resistance between ECM connec-
tor and chassis ground.
Connector & terminal
(B137) No. 29 — Chassis ground:
(B137) No. 25 — Chassis ground:
5 CHECK POWER SUPPLY OF ACCELERA-
TOR POSITION SENSOR.
1) Connect the ECM connector.
2) Turn the ignition switch to ON.
3) Measure the voltage between accelerator
position sensor connector and engine ground.
Connector & terminal
(B315) No. 3 (+) — Engine ground (
6 CHECK ACCELERATOR POSITION SEN-
SOR.
Measure the resistance of accelerator position
sensor.
Terminals
No. 3 — No. 4:
7 CHECK ACCELERATOR POSITION SEN-
SOR.
Measure the resistance of accelerator position
sensor.
Terminals
No. 5 — No. 4:
Check the measured value is within the specifi-
cation without depressing the accelerator
pedal.
Check
Is the voltage more than 0.4 V? Go to step 2.
Is there poor contact?
Is the resistance less than 1
&?
Is the resistance more than 1
M&?
Is the voltage 4.5 — 5.5 V?
"
):
Is the resistance 1.2 — 4.8
k&?
Is the resistance 0.2 — 1.0
k&?
EN(H4SO 2.0)(diag)-207
ENGINE (DIAGNOSTICS)
Yes
Go to step 3.
Repair the poor Temporary poor
contact. contact occurred,
but it is normal at
present.
Go to step 4. Repair the open
circuit of harness
connector.
Go to step 5. Repair the chas-
sis short circuit of
harness.
Go to step 6. Repair the poor
contact in ECM
connector.
Replace the ECM
if defective. <Ref.
to FU(H4SO 2.0)-
34, Engine Con-
trol Module
(ECM).>
Go to step 7. Replace the accel-
erator position
sensor.
Go to step 8. Replace the accel-
erator position
sensor.
No