Subaru Legacy 2003 Service Manual page 576

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)
Step
1 CHECK HARNESS BETWEEN KNOCK SEN-
SOR AND ECM CONNECTOR.
Measure resistance of harness between ECM
connector and chassis ground.
Connector & terminal
(B135) No. 16 — Chassis ground:
Is the measured value less than the specified
value?
2 CHECK KNOCK SENSOR.
1) Disconnect connector from knock sensor.
2) Measure resistance between knock sensor
connector terminal and engine ground.
Terminal
No. 2 — Engine ground:
Is the measured value less than the speci-
fied value?
3 CHECK INPUT SIGNAL FOR ECM.
1) Connect connectors to ECM and knock
sensor.
2) Turn ignition switch to ON.
3) Measure voltage between ECM and chas-
sis ground.
Connector & terminal
(B135) No. 16 (+) — Chassis ground ( − − − − ):
Does the measured value exceed the spec-
ified value?
Value
400 kΩ
400 kΩ
2 V
EN(H4SO)-179
ENGINE (DIAGNOSTICS)
Yes
Go to step 2. Go to step 3.
Replace knock Repair ground
sensor. <Ref. to short circuit in har-
FU(H4SO)-29, ness between
Knock Sensor.> knock sensor con-
nector and ECM
connector.
NOTE:
The harness be-
tween both con-
nectors
shielded.
short circuit of har-
ness together with
shield.
Even if MI lights Repair poor con-
up, the circuit has tact in ECM con-
returned to a nor- nector.
mal condition at
this time. (How-
ever, the possibil-
ity 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
No
is
Repair