Subaru Legacy 2003 Service Manual page 491

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)
ENGINE (DIAGNOSTICS)
6 CHECK OUTPUT SIGNAL FROM ECM.
Measure voltage between ECM connector and
chassis ground.
Connector & terminal
(B136) No. 6 (+) — Chassis ground ( − − − − ):
(B136) No. 17 (+) — Chassis ground ( − − − − ):
Is the measured value less than the specified
value shaking harness and connector of ECM
while monitoring the value with voltage meter?
7 CHECK FRONT OXYGEN (A/F) SENSOR.
1) Turn ignition switch to OFF.
2) Measure resistance between front oxygen
(A/F) sensor connector terminals.
Terminals
No. 3— No. 4:
Is the measured value less than the speci-
fied value?
Step Value
1.0 V
10 Ω
EN(H4SO)-94
Yes
Repair poor con- Go to step 7.
tact in ECM con-
nector.
Repair harness Replace front oxy-
and connector. gen (A/F) sensor.
<Ref. to
NOTE:
FU(H4SO)-41,
In this case, repair
Front Oxygen (A/
the following:
F) Sensor.>
• Open or ground
short circuit in har-
ness between
front oxygen (A/F)
sensor and ECM
connector
• Poor contact in
front oxygen (A/F)
sensor connector
• Poor contact in
ECM connector
No