Subaru IMPREZA GD 2007 Series Manual page 283

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Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step
1 CHECK HARNESS BETWEEN ECM AND
KNOCK SENSOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from the ECM.
3) Measure the resistance between ECM con-
nectors.
Connector & terminal
(B134) No. 15 — (B134) No. 29:
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 ECM.
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 500
kΩ?
Is the resistance less than 500
kΩ?
Is the voltage 2 V or more?
EN(H4SO)(diag)-174
Yes No
Go to step 2. Go to step 3.
Replace the knock Repair short cir-
sensor. <Ref. to cuit of the harness
FU(H4SO)-25, to ground between
Knock Sensor.> the ECM and
knock sensor con-
nector.
NOTE:
The harness be-
tween both con-
nectors are
shielded. Remove
the shield and re-
pair the short cir-
cuit of the harness
circuit.
Even if the malfunc- Repair poor con-
tion indicator light tact of the ECM
illuminates, the cir- connector.
cuit has returned to
a normal condition
at this time. Repro-
duce the fault con-
dition, and
reperform the
check.
NOTE:
In this case, there
may be a tempo-
rary connector
contact failure.