Subaru Legacy 2003 Service Manual page 1976

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)
Step
1 CHECK HARNESS BETWEEN KNOCK SEN-
SOR AND ECM CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Measure the resistance between ECM har-
ness connector and chassis ground.
Connector & terminal
(B135) No. 4 — Chassis ground:
Does the measured value exceed the spec-
ified value?
2 CHECK KNOCK SENSOR.
1) Disconnect the connector from knock sen-
sor.
2) Measure the resistance between knock
sensor connector terminal and engine
ground.
Terminal
No. 2 — Engine ground:
Does the measured value exceed the spec-
ified value?
3 CHECK CONDITION OF KNOCK SENSOR
INSTALLATION.
Is the knock sensor installation bolt tightened
securely?
Value
700 kΩ
700 kΩ
Tightened securely.
EN(H4DOSTC)-137
ENGINE (DIAGNOSTICS)
Yes
Go to step 2. Repair the har-
ness and connec-
tor.
NOTE:
In this case, repair
the following:
• Open circuit in
harness between
knock sensor and
ECM connector
• Poor contact in
knock sensor 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 in
harness between
knock sensor and
ECM connector
• Poor contact in
knock sensor con-
nector
• Poor contact in
coupling connector
Replace the knock Tighten the knock
sensor. <Ref. to sensor installation
FU(H4DOSTC)- bolt securely.
31, Knock Sen-
sor.>
No