Subaru 2009 IMPREZA Service Manual page 494

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 to
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 the ignition
coil and ignitor assembly.
3) Turn the ignition switch to ON.
4) Measure the voltage between ignition coil
and ignitor assembly connector and engine
ground.
Connector & terminal
(E12) No. 2 (+) — Engine ground (–):
3 CHECK HARNESS BETWEEN ECM AND IG-
NITION COIL AND IGNITOR ASSEMBLY.
1) Turn the ignition switch to OFF.
2) Measure the resistance between ECM and
the ignition coil and ignitor assembly connector.
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 assem-
bly 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 cylin-
der?
Is the voltage 10 V or more?
Is the resistance less than 1 ? Go to step 4.
Is the resistance between 10 and
15 k ?
Does the voltage vary 10 V or
more?
EN(H4SO)(diag)-77
Check Yes
Check fuel pump
system. <Ref. to
EN(H4SO)(diag)-
79, FUEL PUMP
CIRCUIT, Diag-
nostics for Engine
Starting Failure.>
Go to step 3.
Go to step 5.
Go to step 6.
ENGINE (DIAGNOSTICS)
No
Go to step 2.
Repair the harness
and connector.
NOTE:
In this case, repair
the following item:
• Open circuit in
harness between
ignition coil and ig-
nitor assembly and
IG relay connector
• Poor contact of
coupling connector
• Blown out of fuse
Repair the harness
and connector.
NOTE:
In this case, repair
the following item:
• Open circuit in
harness between
ECM and ignition
coil and ignitor as-
sembly connector
• Poor contact of
coupling connector
Replace the igni-
tion coil and ignitor
assembly. <Ref. to
IG(H4SO)-6, Igni-
tion Coil and Ignitor
Assembly.>
Replace the igni-
tion coil and ignitor
assembly. <Ref. to
IG(H4SO)-6, Igni-
tion Coil and Ignitor
Assembly.>