Subaru Legacy IV (2008 year). Manual - part 145
EN(H4SO)(diag)-183
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step
Check
Yes
No
1
CHECK HARNESS BETWEEN ECM AND
KNOCK SENSOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from ECM.
3) Measure the resistance between ECM con-
nectors.
Connector & terminal
(B134) No. 15 — (B134) No. 29:
Is the resistance less than
500 k
:?
Go to step 2.
Go to step 3.
2
CHECK KNOCK SENSOR.
1) Disconnect the connector from knock sen-
sor.
2) Measure the resistance between knock
sensor terminals.
Terminals
No. 1 — No. 2:
Is the resistance less than
500 k
:?
Replace the knock
sensor. <Ref. to
FU(H4SO)-25,
Knock Sensor.>
Repair the short
circuit to ground in
harness between
ECM and knock
sensor connector.
NOTE:
The harness be-
tween both con-
nectors are
shielded. Remove
the shield and re-
pair the short cir-
cuit of harness.
3
CHECK INPUT SIGNAL OF ECM.
1) Connect the connector to ECM.
2) Turn the ignition switch to ON.
3) Measure the voltage between ECM and
chassis ground.
Connector & terminal
(B134) No. 15 (+) — Chassis ground (–):
Is the voltage 2 V or more?
Even if DTC is
detected, the cir-
cuit has returned to
a normal condition
at this time. Repro-
duce the failure,
and then perform
the diagnosis
again.
NOTE:
In this case, tem-
porary poor con-
tact of connector
may be the cause.
Repair the poor
contact of ECM
connector.