Subaru IMPREZA 2004 Service Manual page 373

Step
1 CHECK IGNITION SYSTEM FOR SPARKS.
1)Remove the plug cord cap from each spark
plug.
2)Install the new spark plug on plug cord cap.
CAUTION:
Do not remove the spark plug from engine.
3)Contact the spark plug's 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 & IGNITOR ASSY.
1)Turn the ignition switch to OFF.
2)Disconnect the connector from ignition coil &
ignitor ASSY.
3)Turn the ignition switch to ON.
4)Measure the power supply voltage between
ignition coil & ignitor ASSY connector and
engine ground.
Connector & terminal
1.6 L: (E12) No. 1 (+) — Engine ground
( − − − − ):
2.0 L: (E12) No. 2 (+) — Engine ground
( − − − − ):
3 CHECK HARNESS OF IGNITION COIL & IG-
NITOR ASSY GROUND CIRCUIT.
1)Turn the ignition switch to OFF.
2)Measure the resistance between ignition coil
& ignitor ASSY connector and engine ground.
Connector & terminal
(E12) No. 3 — Engine ground:
4 CHECK IGNITION COIL & IGNITOR ASSY.
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
& IGNITOR ASSY.
1)Connect the connector to ignition coil & igni-
tor ASSY.
2)Check if voltage varies synchronously with
engine speed when cranking, while monitoring
voltage between ignition coil & ignitor ASSY
connector and engine ground.
Connector & terminal
1.6 L: (E12) No. 4 (+) — Engine ground
(–):
2.0 L: (E12) No. 1 (+) — Engine ground
(–):
1.6 L: (E12) No. 2 (+) — Engine ground
(–):
2.0 L: (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 10 — 15 kΩ? Go to step 5.
Is the voltage more than 10 V? Go to step 6.
EN(H4SO)(diag)-67
Check
Check fuel pump
system. <Ref. to
EN(H4SO)(diag)-
69, FUEL PUMP
CIRCUIT, Diag-
nostics for Engine
Starting Failure.>
Go to step 4.
ENGINE (DIAGNOSTICS)
Yes No
Go to step 2.
Repair harness
and connector.
NOTE:
In this case, repair
the following:
• Open circuit in
harness between
ignition coil & igni-
tor ASSY, and igni-
tion switch
connector
• Poor contact in
coupling connec-
tors
Repair harness
and connector.
NOTE:
In this case, repair
the following:
• Open circuit in
harness between
ignition coil & igni-
tor ASSY connec-
tor and engine
grounding terminal
Replace the igni-
tion coil & ignitor
ASSY. <Ref. to
IG(H4SO)-8, Igni-
tion Coil & Ignitor
ASSY.>
Replace the igni-
tion coil & ignitor
ASSY. <Ref. to
IG(H4SO)-8, Igni-
tion Coil & Ignitor
ASSY.>