Subaru LEGACY 2006 Manual page 220

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Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step
1 CHECK HARNESS BETWEEN KNOCK SEN-
SOR AND ECM CONNECTOR.
Measure the resistance of harness between
ECM connector and chassis ground.
Connector & terminal
(B134) No. 15 — Chassis ground:
2 CHECK KNOCK SENSOR.
1) Disconnect the connector from knock sen-
sor.
2) Measure the resistance between knock
sensor connector terminals.
Terminals
No. 1 — No. 2:
3 CHECK INPUT SIGNAL OF ECM.
1) Connect the connectors to ECM and knock
sensor.
2) Turn the ignition switch to ON.
3) Measure the voltage between ECM and
chassis ground.
Connector & terminal
(B134) No. 15 (+) — Chassis ground (–):
Check
Is the resistance less than 400
kΩ?
Is the resistance less than 400
kΩ?
Is the voltage more than 2 V?
EN(H4SO)(diag)-183
ENGINE (DIAGNOSTICS)
Yes No
Go to step 2. Go to step 3.
Replace the knock Repair the ground
sensor. <Ref. to short circuit of har-
FU(H4SO)-22, ness between
Knock Sensor.> knock sensor con-
nector and ECM
connector.
NOTE:
The harness be-
tween both con-
nectors
shielded. Repair the
short circuit of har-
ness covered with
shield.
Even if the mal- Repair the poor
function indicator contact of ECM
light illuminates, connector.
the circuit has
returned to a nor-
mal condition at
this time. (How-
ever, the possibility
of poor contact still
remains.)
NOTE:
In this case, repair
the following item:
• Poor contact of
knock sensor con-
nector
• Poor contact in
ECM connector
• Poor contact of
coupling connector
are