Subaru IMPREZA GD 2007 Series Manual page 275

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Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step
1 CHECK OUTPUT SIGNAL OF ECM.
1) Turn the ignition switch to ON.
2) Measure the voltage between the ECM and
chassis ground for faulty cylinders.
Connector & terminal
#1 (B137) No. 8 (+) — Chassis ground (–):
#2 (B137) No. 9 (+) — Chassis ground (–):
#3 (B137) No. 10 (+) — Chassis ground (–):
#4 (B137) No. 11 (+) — Chassis ground (–):
2 CHECK HARNESS BETWEEN ECM AND
FUEL INJECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from fuel injector
on faulty cylinders.
3) Measure the resistance between the fuel
injector connector and engine ground on faulty
cylinders.
Connector & terminal
#1 (E5) No. 1 — Engine ground:
#2 (E16) No. 1 — Engine ground:
#3 (E6) No. 1 — Engine ground:
#4 (E17) No. 1 — Engine ground:
3 CHECK HARNESS BETWEEN ECM AND
FUEL INJECTOR.
Measure the resistance of harness between the
ECM and fuel injector on faulty cylinders.
Connector & terminal
#1 (B137) No. 8 — (E5) No. 1:
#2 (B137) No. 9 — (E16) No. 1:
#3 (B137) No. 10 — (E6) No. 1:
#4 (B137) No. 11 — (E17) No. 1:
4 CHECK FUEL INJECTOR.
Measure the resistance between fuel injector
terminals on faulty cylinder.
Terminals
No. 1 — No. 2:
5 CHECK POWER SUPPLY LINE.
1) Turn the ignition switch to ON.
2) Measure the voltage between fuel injector
and engine ground on faulty cylinders.
Connector & terminal
#1 (E5) No. 2 (+) — Engine ground (–):
#2 (E16) No. 2 (+) — Engine ground (–):
#3 (E6) No. 2 (+) — Engine ground (–):
#4 (E17) No. 2 (+) — Engine ground (–):
Check
Is the voltage 10 V or more?
Is the resistance 1 MΩ or
more?
Is the resistance less than 1 Ω? Go to step 4.
Is the resistance between 5 —
20 Ω?
Is the voltage 10 V or more?
EN(H4SO)(diag)-166
Yes No
Go to step 6. Go to step 2.
Go to step 3. Repair short cir-
cuit of the harness
to ground between
ECM and fuel
injector.
Repair the harness
and connector.
NOTE:
In this case, repair
the following item:
• Open circuit of
harness between
ECM and fuel in-
jector connector
• Poor contact of
coupling connector
Go to step 5. Replace the faulty
fuel injector. <Ref.
to FU(H4SO)-30,
Fuel Injector.>
Repair the poor Repair the harness
contact of all con- and connector.
nectors in fuel
NOTE:
injector circuit.
In this case, repair
the following item:
• Open circuit of
harness between
the main relay and
fuel injector con-
nector on faulty
cylinders
• Poor contact of
coupling connector
• Poor contact of
main relay connec-
tor
• Poor contact of
fuel injector con-
nector on faulty
cylinders