Subaru LEGACY 2006 Manual page 971

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ENGINE (DIAGNOSTICS)
Step
1 CHECK IGNITION SYSTEM FOR SPARKS.
1) Remove the plug cord cap from each spark
plug.
2) Install a new spark plug on plug cord cap.
CAUTION:
Do not remove the spark plug from engine.
3) Contact the spark plug thread portion on
engine.
4) While opening the throttle valve fully, crank
the engine to check that spark occurs at each
cylinder.
2 CHECK POWER SUPPLY CIRCUIT FOR IG-
NITION COIL AND IGNITOR ASSEMBLY.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ignition coil
and ignitor assembly.
3) Turn the ignition switch to ON.
4) Measure the power supply voltage between
ignition coil and ignitor assembly connector
and engine ground.
Connector & terminal
(E12) No. 2 (+) — Engine ground (–):
3 CHECK HARNESS BETWEEN IGNITION
COIL AND IGNITOR ASSEMBLY, AND ECM.
1) Turn the ignition switch to OFF.
2) Measure the resistance between the igni-
tion coil and ignitor assembly connector, and
ECM.
Connector & terminal
(E12) No. 3 — (B137) No. 6:
(E12) No. 3 — (B137) No. 26:
4 CHECK IGNITION COIL AND IGNITOR AS-
SEMBLY.
1) Remove the spark plug cords.
2) Measure the resistance between spark
plug cord contact portions to check secondary
coil.
Terminals
No. 1 — No. 2:
No. 3 — No. 4:
5 CHECK INPUT SIGNAL FOR IGNITION COIL
AND IGNITOR ASSEMBLY.
1) Connect the connector to the Ignition coil
and ignitor assembly.
2) Check if voltage varies synchronously with
engine speed when cranking, while monitoring
voltage between ignition coil and ignitor
assembly connector and engine ground.
Connector & terminal
(E12) No. 1 (+) — Engine ground (–):
(E12) No. 4 (+) — Engine ground (–):
Diagnostics for Engine Starting Failure
Does spark occur at each cyl-
inder?
Is the voltage more than 10 V? Go to step 3.
Is the resistance less than 5
Ω?
Is the resistance between 10
and 15 kΩ?
Does the voltage vary more
than 10 V?
EN(H4SO U5)(diag)-66
Check Yes
Check fuel pump
system. <Ref. to
EN(H4SO
U5)(diag)-68,
FUEL PUMP CIR-
CUIT, Diagnostics
for Engine Start-
ing Failure.>
Go to step 4.
Go to step 5.
Go to step 6.
No
Go to step 2.
Repair the har-
ness and connec-
tor.
NOTE:
In this case, repair
the following item:
• Open circuit of
harness between
the ignition coil and
ignitor assembly,
and main relay
connector
• Poor contact of
coupling connector
• Blown out of
fuse
Repair the har-
ness and connec-
tor.
NOTE:
In this case, repair
the following item:
Open circuit in har-
ness between igni-
tion coil and ignitor
assembly connec-
tor, and ECM
Replace the igni-
tion coil and ignitor
assembly. <Ref. to
IG(H4SO)-7, Igni-
tion Coil and Igni-
tor Assembly.>
Replace the igni-
tion coil and ignitor
assembly. <Ref. to
IG(H4SO)-7, Igni-
tion Coil and Igni-
tor Assembly.>