Subaru Forester 2004 Service Manual page 61

ENGINE (DIAGNOSTIC)
Step
1 CHECK SPARK PLUG CONDITION.
1) Remove the spark plug. <Ref. to
IG(H4DOTC)-6, INSTALLATION, Spark Plug.>
2) Check the spark plug condition. <Ref. to
IG(H4DOTC)-6, INSPECTION, Spark Plug.>
2 CHECK IGNITION SYSTEM FOR SPARKS.
1) Connect the spark plug to ignition coil.
2) Release the fuel pressure. <Ref. to
FU(H4DOTC 2.5)-45, RELEASING OF FUEL
PRESSURE, OPERATION, Fuel.>
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.
3 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
(E31) No. 3 (+) — Engine ground (
(E32) No. 3 (+) — Engine ground (
(E33) No. 3 (+) — Engine ground (
(E34) No. 3 (+) — Engine ground (
4 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
(E31) No. 2 — Engine ground:
(E32) No. 2 — Engine ground:
(E33) No. 2 — Engine ground:
(E34) No. 2 — Engine ground:
5 CHECK HARNESS BETWEEN ECM AND IG-
NITION COIL & IGNITOR ASSY CONNEC-
TOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Disconnect the connector from ignition coil
& ignitor ASSY.
4) Measure the resistance of harness
between ECM and ignition coil & ignitor ASSY
connector.
Connector & terminal
(B135) No. 15 — (E34) No. 1:
(B135) No. 16 — (E33) No. 1:
(B135) No. 17 — (E32) No. 1:
(B135) No. 18 — (E31) No. 1:
Diagnostics for Engine Starting Failure
Is the spark plug's status OK? Go to step 2.
Does spark occur at each cyl-
inder?
Is the voltage more than 10 V? Go to step 4.
−
):
−
):
−
):
−
):
Is the resistance less than 5
Ω?
Is the resistance less than 1
Ω?
EN(H4DOTC 2.5)-60
Check
Check fuel pump
system. <Ref. to
EN(H4DOTC 2.5)-
62, FUEL PUMP
CIRCUIT, Diag-
nostics for Engine
Starting Failure.>
Go to step 5.
Go to step 6.
Yes No
Replace the spark
plug.
Go to step 3.
Repair the 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 connector
Repair the harness
and connector.
NOTE:
In this case repair
the following:
• Open circuit in
harness between
ignition coil & igni-
tor ASSY connec-
tor and engine
ground terminal
Repair the harness
and connector.
NOTE:
In this case repair
the following:
• OPEN CIR-
CUIT IN HAR-
NESS BETWEEN
ECM AND IGNI-
TION COIL &
IGNITOR ASSY
CONNECTOR.
• Poor contact in
coupling connector