Subaru Legacy 2005 Service Manual page 1380

Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step
1 CHECK POWER SUPPLY CIRCUIT OF IGNI-
TION COIL.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ignition coil.
3) Turn the ignition switch to ON.
4) Measure the power supply voltage between
ignition coil 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 (
2 CHECK HARNESS OF ECM AND IGNITION
COIL GROUND CIRCUIT.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Measure the resistance between ignition
coil 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:
3 CHECK HARNESS BETWEEN ECM AND IG-
NITION COIL CONNECTOR.
1) Disconnect the connector from ignition coil.
2) Measure the resistance of harness
between ECM and ignition coil connector.
Connector & terminal
(B135) No. 18 — (E31) No. 1:
(B135) No. 17 — (E32) No. 1:
(B135) No. 16 — (E33) No. 1:
(B135) No. 15 — (E34) No. 1:
4 CHECK HARNESS BETWEEN ECM AND IG-
NITION COIL CONNECTOR.
Measure the resistance of harness between
ignition coil connector and engine ground.
Connector & terminal:
(E31) No. 1 — Engine ground:
(E32) No. 1 — Engine ground:
(E32) No. 1 — Engine ground:
(E34) No. 1 — Engine ground:
Check
Is the voltage more than 10 V? Go to step 2.
−
):
−
):
−
):
−
):
Is the resistance less than 5
Ω?
Is the resistance less than 1
Ω?
Is the resistance more than 1
MΩ?
EN(H4DOTC)(diag)-140
Yes
Repair the har-
ness and connec-
tor.
NOTE:
In this case, repair
the following:
• Open circuit of
harness between
ignition coil and
ignition switch con-
nector
• Poor contact in
coupling connector
Go to step 3. Repair the har-
ness and connec-
tor.
NOTE:
In this case, repair
the following:
• Open circuit of
harness between
ignition coil con-
nector and engine
ground terminal
• Poor contact in
coupling connector
Go to step 4. Repair the har-
ness and connec-
tor.
NOTE:
In this case, repair
the following:
• Open circuit of
harness between
ECM and ignition
coil connector
• Poor contact in
coupling connector
Repair the poor Repair the har-
contact in terminal. ness and connec-
tor.
No