Subaru 2002 IMPREZA Service Manual page 527

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)
ENG IN E (DIAGNOSTICS)
Step
CHECK HARNESS BETWEEN ECM AND
FRONT OXYGEN (NF) SENSOR CONNEC-
TOR.
1)Turn the ignition switch to OFF.
2)Disconnect the connector from ECM.
3)Measure the resistance of harness between
ECM connector and chassis ground.
Connector & terminal
(8137) No. 19
-
Chassis ground:
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
(8137) No. 29
-
Chassis ground:
CHECK OUTPUT SIGNAL FOR ECM.
1)Connect the connector to ECM.
2)Turn the ignition switch to ON.
3)Measure the voltage between ECM connec-
tor and chassis ground.
Connector & terminal
(8137) No. 19 (+)
-
Chassis ground ( - ) :
CHECK OUTPUT SIGNAL FOR ECM.
Measure the voltage between ECM connector
and chassis ground.
Connector & terminal
(8137) No. 19 (+)
-
Chassis ground ( - ) :
CHECK OUTPUT SIGNAL FOR ECM.
Measure the voltage between ECM connector
and chassis ground.
Connector & terminal
(6137) No. 29 (+)
-
Chassis ground (-):
CHECK OUTPUT SIGNAL FOR ECM.
Measure the voltage between ECM connector
and chassis ground.
Connector & terminal
(8 137) No. 29 (+)
-
Chassis ground (-):
Check
the resistance more than 10
?
the resistance more than 10
?
the voltage more than 4.5 V?
the voltage more than 10 V?
the voltage more than 4.95
b
the voltage more than 10 V?
Yes
Go to step 2.
Go to step 3.
Go to step 4.
Repair battery
short circuit in har-
ness between
ECM and front
oxygen (NF) sen-
sor connector.
Go to step 6.
Repair battery
short circuit in har-
nessbetween
ECM and front
oxygen (NF) sen-
sor connector.
No
Repair ground
short circuit in har
ness between
ECM and front
oxygen
(NF)
sen-
sor connector.
Repair ground
short circuit in har
ness between
ECM and front
oxygen (NF) sen-
sor connector.
Go to step 5.
Repair poor con-
tact in ECM con-
nector.
Replace the front
oxygen (NF) sen-
sor. <Ref. to
FU(D0HC
TURBO)-42, Froni
Oxygen (NF) Sen
sor.>
Repair poor con-
tact in ECM con-
nector.
EN(D0HC TURBO)-303