Subaru IMPREZA GD 2007 Series Manual page 273

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Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step
1 CHECK HARNESS BETWEEN ECM AND
ELECTRONIC THROTTLE CONTROL.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from ECM and
electronic throttle control.
3) Measure the resistance of harness between
ECM and electronic throttle control connector.
Connector & terminal
(B134) No. 28 — (E57) No. 4:
(B134) No. 29 — (E57) No. 3:
2 CHECK HARNESS BETWEEN ECM AND
ELECTRONIC THROTTLE CONTROL.
1) Connect the ECM.
2) Measure the resistance between electronic
throttle control connector and engine ground.
Connector & terminal
(E57) No. 3 — Engine ground:
3 CHECK HARNESS BETWEEN ECM AND
ELECTRONIC THROTTLE CONTROL.
1) Turn the ignition switch to ON.
2) Measure the voltage between electronic
throttle control connector and engine ground.
Connector & terminal
(E57) No. 4 (+) — Engine ground (–):
4 CHECK HARNESS BETWEEN ECM AND
ELECTRONIC THROTTLE CONTROL.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from the ECM.
3) Measure the resistance between ECM con-
nectors.
Connector & terminal
(B134) No. 19 — (B134) No. 28:
AT:DTC P0301 CYLINDER 1 MISFIRE DETECTED
NOTE:
For the diagnostic procedure, refer to DTC P0304. <Ref. to EN(H4SO)(diag)-165, DTC P0304 CYLINDER 4
MISFIRE DETECTED, Diagnostic Procedure with Diagnostic Trouble Code (DTC).>
AU:DTC P0302 CYLINDER 2 MISFIRE DETECTED
NOTE:
For the diagnostic procedure, refer to DTC P0304. <Ref. to EN(H4SO)(diag)-165, DTC P0304 CYLINDER 4
MISFIRE DETECTED, Diagnostic Procedure with Diagnostic Trouble Code (DTC).>
AV:DTC P0303 CYLINDER 3 MISFIRE DETECTED
NOTE:
For the diagnostic procedure, refer to DTC P0304. <Ref. to EN(H4SO)(diag)-165, DTC P0304 CYLINDER 4
MISFIRE DETECTED, Diagnostic Procedure with Diagnostic Trouble Code (DTC).>
Check
Is the resistance less than 1 Ω? Go to step 2.
Is the resistance less than 5 Ω? Go to step 3.
Is the voltage 4.85 V or more? Repair the short
Is the resistance 1 MΩ or
more?
EN(H4SO)(diag)-164
Yes No
Repair the open
circuit of harness
between ECM and
electronic throttle
control connector.
Repair the harness
and connector.
NOTE:
In this case, repair
the following item:
• Open circuit of
harness between
ECM and engine
ground
• Poor contact in
ECM connector
• Poor contact of
coupling connector
Go to step 4.
circuit to power in
the harness
between ECM and
electronic throttle
control connector.
Repair poor con- Repair the short
tact of the elec- circuit to power in
tronic throttle the harness
control connector. between ECM and
Replace the elec- electronic throttle
tronic throttle con- control connector.
trol if defective.
<Ref. to
FU(H4SO)-12,
Throttle Body.>