Subaru Legacy (2005 year). Manual - part 469
EN(H6DO)(diag)-189
ENGINE (DIAGNOSTICS)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step
Check
Yes
No
1
CHECK HARNESS BETWEEN KNOCK SEN-
SOR AND ECM CONNECTOR.
Measure the resistance of harness between
ECM connector and chassis ground.
Connector & terminal
(B136) No. 25 — Chassis ground:
Is the resistance less than 400
k
Ω?
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:
Is the resistance less than 400
k
Ω?
Replace the knock
sensor. <Ref. to
FU(H6DO)-21,
Knock Sensor.>
Repair the ground
short circuit of har-
ness between
knock sensor con-
nector and ECM
connector.
NOTE:
The harness be-
tween both con-
nectors are
shielded. Repair
the short circuit of
harness covered
with shield.
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
(B136) No. 25 (+) — Chassis ground (
−
):
Is the voltage more than 2 V?
Even if the mal-
function indicator
light illuminates,
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:
• Poor contact in
knock sensor con-
nector
• Poor contact in
ECM connector
• Poor contact in
coupling connector
Repair the poor
contact in ECM
connector.