Subaru 2002 IMPREZA Service Manual page 667

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)
Step
1 CHECK CURRENT DATA.
1)Start the engine.
2)Read the data of intake manifold absolute
pressure signal 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-34, Subaru Select Monitor.>
•OBD-II general scan tool
For detailed operation procedures, refer to the
OBD-II General Scan Tool Instruction Manual.
2 CHECK INPUT SIGNAL FOR ECM.
Measure the voltage between ECM connector
and chassis ground.
Connector & terminal
(B136) No. 15 (+) — Chassis ground ( − − − − ):
3 CHECK INPUT SIGNAL FOR ECM.
Measure the voltage between ECM connector
and chassis ground.
Connector & terminal
(B136) No. 15 (+) — Chassis ground ( − − − − ):
4 CHECK INPUT SIGNAL FOR ECM.
Measure the voltage between ECM connector
and chassis ground.
Connector & terminal
(B136) No. 29 (+) — Chassis ground ( − − − − ):
5 CHECK INPUT SIGNAL FOR ECM. (USING
SUBARU SELECT MONITOR.)
Read the data of atmospheric absolute pres-
sure signal using Subaru Select Monitor.
NOTE:
•Subaru Select Monitor
For detailed operation procedure, refer to the
"READ CURRENT DATA FOR ENGINE".
<Ref. to EN-34, Subaru Select Monitor.>
6 CHECK HARNESS BETWEEN ECM AND
PRESSURE SENSOR CONNECTOR.
1)Turn the ignition switch to OFF.
2)Disconnect the connector from atmospheric
pressure sensor.
3)Turn the ignition switch to ON.
4)Measure the voltage between atmospheric
pressure sensor connector and engine ground.
Connector & terminal
(B2) No. 3 (+) — Engine ground ( − − − − ):
Check
Is the value more than 140 kPa
(1,050 mmHg, 41.34 inHg)?
Is the voltage more than 4.5 V? Go to step 4.
Does the voltage change more
than 4.5 V by shaking harness
and connector of ECM while
monitoring the value with volt-
age meter?
Is the voltage less than 0.2 V? Go to step 6.
Does the value change more
than 0 kPa (0 mmHg, 0 inHg)
by shaking harness and con-
nector of ECM while monitor-
ing the value with Subaru
Select Monitor?
Is the voltage more than 4.5 V? Go to step 7.
EN-235
ENGINE (DIAGNOSTICS)
Yes
Go to step 10. Go to step 2.
Go to step 3.
Repair the poor Contact with your
contact in ECM Subaru distributor
connector. service.
NOTE:
Inspection by DTM
is required,
cause
cause is deteriora-
tion of
parts.
Go to step 5.
Repair the poor Go to step 6.
contact in ECM
connector.
Repair the har-
ness and connec-
tor.
NOTE:
In this case, repair
the following:
• Open circuit in
harness between
ECM and pressure
sensor connector
• Poor contact in
joint connector
(B83) or (B122)
No
be-
probable
multiple