Subaru IMPREZA GD 2007 Series Manual page 372

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Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step
1 CHECK POWER SUPPLY TO EGR VALVE.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from EGR valve.
3) Turn the ignition switch to ON.
4) Measure the voltage between EGR valve
connector and engine ground.
Connector & terminal
(E18) No. 2 (+) — Engine ground (–):
(E18) No. 5 (+) — Engine ground (–):
2 CHECK HARNESS BETWEEN ECM AND
EGR VALVE CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from the ECM.
3) Measure the resistance between ECM and
EGR valve connector.
Connector & terminal
DTC P1492; (B134) No. 8 — (E18) No. 3:
DTC P1494; (B134) No. 9 — (E18) No. 1:
DTC P1496; (B134) No. 10 — (E18) No. 4:
DTC P1498; (B134) No. 20 — (E18) No. 6:
3 CHECK HARNESS BETWEEN ECM AND
EGR VALVE CONNECTOR.
1) Disconnect the connectors from the ECM.
2) Measure the resistance between ECM and
chassis ground.
Connector & terminal
DTC P1492; (B134) No. 8 — Chassis
ground:
DTC P1494; (B134) No. 9 — Chassis
ground:
DTC P1496; (B134) No. 10 — Chassis
ground:
DTC P1498; (B134) No. 20 — Chassis
ground:
4 CHECK POOR CONTACT.
Check the poor contact in ECM and EGR valve
connector.
Check
Is the voltage 10 V or more?
Is the resistance less than 1 Ω? Go to step 3.
Is the resistance 1 MΩ or
more?
Is there poor contact in ECM or
EGR valve connector?
EN(H4SO)(diag)-263
ENGINE (DIAGNOSTICS)
Yes No
Go to step 2. Repair the harness
and connector.
NOTE:
In this case, repair
the following item:
• Open circuit in
harness between
EGR valve and
main relay connec-
tor
• Poor contact of
coupling connector
Repair the harness
and connector.
NOTE:
In this case, repair
the following item:
• Open circuit in
harness between
ECM and EGR
valve connector
• Poor contact of
coupling connector
Go to step 4. Repair short cir-
cuit of the harness
to ground between
ECM and EGR
valve connector.
Repair the poor Replace the EGR
contact in ECM or valve. <Ref. to
EGR valve con- FU(H4SO)-29,
nector. EGR Valve.>