Subaru IMPREZA 2002 Service Manual page 415

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)
ENGINE (DIAGNOSTICS)
Step
CHECK GROUND CIRCUIT OF ECM.
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
(8134) No. 35
-
Chassis ground:
CHECK GROUND CIRCUIT OF ECM.
1)Repair the harness and connector.
NOTE:
In this case, repair the following:
*Open circuit in harness between ECM and
engine ground terminal
*Poor contact in ECM connector
*Poor contact in coupling connector (B22)
1)Measure resistance of harness between
ECM connector and chassis ground.
I
Connector & terminal
(8134) No. 34
-
Chassis ground:
I
CHECK CURRENT DATA.
1)Start the engine.
2)Read the data of rear oxygen sensor heater
current using Subaru Select Monitor or OBD-II
general scan
tool.
NOTE:
*Subaru Select Monitor
For detailed operation procedure, refer to the
"READ CURRENT DATA FOR ENGINE. <Ref.
to EN(S0HC)-32, Subaru Select Monitor.>
*OBD-II scan tool
For detailed operation procedures, refer to the
OBD-ll General Scan Tool Instruction Manual.
I CHECK OUTPUT SIGNAL FROM ECM.
1)Start and idle the engine.
2)Measure the voltage between ECM connec-
tor and chassis ground.
Connector & terminal
(8134) No. 21 (+)
-
Chassis ground ( - ) :
CHECK OUTPUT SIGNAL FROM ECM.
Measure the voltage between ECM connector
and chassis ground.
b
Connector & terminal
(8134) No. 21 (+)
-
Chassis ground ( - ) :
CHECK OUTPUT SIGNAL FROM ECM.
1)Disconnect the connector from rear oxygen
sensor.
2)Measure the voltage between ECM connec-
tor and chassis ground.
i
Connector & terminal
(B 134) No. 21 (+)
-
Chassis ground ( - ) :
Check
;the resistance less than 5
2?
s the resistance less than 5
L?
s
the value more than 0.2 A?
s the voltage less than 1 .O V?
>oes the voltage change less
han 1 .O V by shaking harness
ind connector of ECM while
nonitoring the value with volt-
ige meter?
s the voltage less than 1 .O V?
Yes
30 to step 3 .
30 to step 3 .
3epair the con-
lector.
UOTE:
n this case, repair
,he following:
1
Poor contact in
.ear oxygen sen-
;or connector
1
Poor contact in
'ear oxygen sen-
:or connecting
iarness connector
1
Poor contact in
ECM connector
30 to step 7.
3epair poor con-
:act in ECM con-
lector.
3eplace the ECM.
<Ref. to
Engine Control
Module.>
FU(S0HC)-47,
No
30 to step 2.
Repair harness
snd connector.
VOTE:
In this case, repair
the following:
b
Open circuit in
harness between
ECM and engine
around terminal
b
Poor contact in
ECM connector
Poor contact in
coupling connector
(B22)
Go to step 4.
Go to step 5.
Go to step 6.
Repair battery
short circuit in har-
ness between
ECM and rear oxy
gen sensor con-
nector. After
repair, replace the
ECM. <Ref. to
Engine Control
Module.>
FU(S0HC)-47,
EN(S0HC)-91