Subaru Legacy 2004 Service Manual page 978

Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step
1 CHECK OPTION CODE.
2 CHECK HARNESS BETWEEN ECM AND
FRONT OXYGEN (A/F) SENSOR CONNEC-
TOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM and
front oxygen (A/F) sensor.
3) Measure the resistance of harness
between ECM connector and chassis ground.
Connector & terminal
(B134) No. 26 — Chassis ground:
3 CHECK HARNESS BETWEEN ECM AND
FRONT OXYGEN (A/F) SENSOR CONNEC-
TOR.
Measure the resistance of harness between
ECM connector and chassis ground.
Connector & terminal
(B134) No. 33 — Chassis ground:
4 CHECK OUTPUT SIGNAL FOR ECM.
1) Connect the connector to ECM and front
oxygen (A/F) sensor.
2) Turn the ignition switch to ON.
3) Measure the voltage between ECM con-
nector and chassis ground.
Connector & terminal
(B134) No. 26 (+) — Chassis ground (
5 CHECK OUTPUT SIGNAL FOR ECM.
Measure the voltage between ECM connector
and chassis ground.
Connector & terminal
(B134) No. 26 (+) — Chassis ground (
6 CHECK OUTPUT SIGNAL FOR ECM.
Measure the voltage between ECM connector
and chassis ground.
Connector & terminal
(B134) No. 33 (+) — Chassis ground (
Check
Is the option code EC, EK or
K4?
Is the resistance more than 1
M!?
Is the resistance more than 1
M!?
Is the voltage more than 4.5 V? Go to step 5.
"
):
Is the voltage more than 10 V? Repair the battery
"
):
Is the voltage more than 4.95
V?
"
):
EN(H4SO 2.5)(diag)-219
ENGINE (DIAGNOSTICS)
Yes
Go to step 2. Refer to EN(H4SO
2.0) section. <Ref.
to EN(H4SO
2.0)(diag)-66, List
of Diagnostic Trou-
ble Code (DTC).>
NOTE:
Fuel injection sys-
tem for KA and KS
model is the same
as 2.0 L model.
Go to step 3. Repair the ground
short circuit in har-
ness between
ECM and front
oxygen (A/F) sen-
sor connector.
Go to step 4. Repair the ground
short circuit in har-
ness between
ECM and front
oxygen (A/F) sen-
sor connector.
Go to step 6.
Repair the poor
short circuit in har- contact in ECM
ness between connector.
ECM and front
oxygen (A/F) sen-
sor connector.
After repair,
replace the ECM.
<Ref. to FU(H4SO
2.5)-36, Engine
Control Module
(ECM).>
Go to step 7. Replace the front
oxygen (A/F) sen-
sor. <Ref. to
FU(H4SO 2.5)-34,
Front Oxygen (A/
F) Sensor.>
No