Subaru IMPREZA 2002 Service Manual page 409

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)
EN G I N E (D I AG NOSTl CS)
Step
!
CHECK POWER SUPPLY TO FRONT OXY-
GEN (NF) SENSOR.
1)Turn the ignition switch to OFF.
2)Disconnect the connector from front oxygen
(NF) sensor.
3)Turn the ignition switch to ON.
4)Measure the voltage between front oxygen
(NF) sensor connector and engine ground.
Connector & terminal
(E24) No. 2 (+)
-
Engine ground
( - ) I
1
CHECK GROUND CIRCUIT OF ECM.
Measure the resistance of harness between
ECM connector and chassis ground.
Connector & terminal
(8134) No. 35
-
Chassis ground:
(8134) No. 34
-
Chassis ground:
1 CHECK CURRENT DATA.
1)Start the engine.
2)Read the data of front oxygen (NF) sensor
heater current using Subaru Select Monitor or
OED-ll general scan tool.
NOTE:
OSubaru Select Monitor
For detailed operation procedure, refer to the
"READ CURRENT DATA FOR ENGINE". <Ref.
to EN(S0HC)-32, Subaru Select Monitor.>
*OED-II scan tool
For detailed operation procedures, refer to the
OED-ll General Scan Tool Instruction Manual.
CHECK OUTPUT SIGNAL FROM ECM.
1)Start and idle the engine.
2)Measure the voltage between ECM connec-
tor and chassis ground.
I
Connector 81 terminal
(8134) No. 22 (+)
-
Chassis ground (-):
CHECK OUTPUT SIGNAL FROM ECM.
Measure the voltage between ECM connector
and chassis ground.
i
Connector & terminal
(8134) No. 22 (+)
-
Chassis ground (-):
CHECK OUTPUT SIGNAL FROM ECM.
Measure the voltage between ECM connector
and chassis ground.
I
Connector & terminal
(8134) No. 23 (+)
-
Chassis ground (-):
Check
the voltage more than 10 V?
the resistance less than 5
?
the value more than 0.2 A?
the voltage less than 1 .O V?
ies the voltage change less
m
1 .O V by shaking harness
id connector of ECM while
mitoring the value with volt-
le meter?
the voltage less than 1 .O
V?
Yes
; o to step 3.
i o
to step 4.
3epair poor con-
act in connector.
IOTE:
n this case, repail
he following:
1
Poor contact in
ront oxygen (NF)
sensor connector
Poor contact in
ICM connector
; o to step
7.
lepair poor con-
act in ECM con-
lector.
; o to step
9.
~
NO
Repair power sup.
ply line.
NOTE:
In this case, repai
the following:
Open circuit in
harness between
main relay and
front oxygen (NF)
sensor connector
Poor contact in
front oxygen (NF)
sensor connector
Poor contact in
main relay connec
tor
Repair harness
and connector.
NOTE:
In this case, repa
the following:
Open circuit in
harness between
ECM and engine
ground terminal
Poor contact in
ECM connector
Poor contact in
coupling connect0
Go to step 5.
(B2.3
Go to step 6.
Go to step 7.
Go to step 8.
EN(S0HC)-85