Subaru Forester 2004 Service Manual page 133

Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTIC)
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
(B136) No. 25 — Chassis ground:
2 CHECK KNOCK SENSOR.
1) Disconnect the connector from knock sensor.
2) Measure the resistance between knock
sensor connector terminal and engine ground.
Connector & terminal
(E14) No. 2 — Engine ground:
3 CHECK CONDITION OF KNOCK SENSOR
INSTALLATION.
Check
Is the resistance more than
700 kΩ?
Is the resistance more than
700 kΩ?
Is the knock sensor installation
bolt tightened securely?
EN(H4DOTC 2.5)-132
Yes
Go to step 2. Repair the harness
and connector.
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 harness
and connector.
NOTE:
In this case repair
the following:
• Poor contact in
knock sensor con-
nector
• Poor contact in
coupling connector
Replace the knock Tighten knock sen-
sensor. <Ref. to sor installation bolt
FU(H4DOTC 2.5)- securely.
29, Knock Sen-
sor.>
No