Subaru Legacy 2002 Service Manual page 636

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)
No.
1 CHECK CURRENT DATA.
1) Start engine.
2) Read data of intake air temperature sensor
signal using Subaru Select Monitor or the
OBD-II general scan tool.
NOTE:
¼ Subaru Select Monitor
For detailed operation procedure, refer to the
"READ CURRENT DATA FOR ENGINE".
<Ref. to EN-34, Subaru Select Monitor.>
¼ OBD-II general scan tool
For detailed operation procedure, refer to the
OBD-II General Scan Tool Instruction Manual.
2 CHECK HARNESS BETWEEN INTAKE AIR
TEMPERATURE AND PRESSURE SENSOR
AND ECM CONNECTOR.
1) Turn ignition switch to OFF.
2) Disconnect connector from intake air tem-
perature and pressure sensor.
3) Measure voltage between intake air tem-
perature and pressure sensor connector and
engine ground.
Connector & terminal
(E20) No. 2 (+) — Engine ground (−):
3 CHECK HARNESS BETWEEN INTAKE AIR
TEMPERATURE AND PRESSURE SENSOR
AND ECM CONNECTOR.
1) Turn ignition switch to ON.
2) Measure voltage between intake air tem-
perature and pressure sensor connector and
engine ground.
Connector & terminal
(E20) No. 2 (+) — Engine ground (−):
Step
Is the value less than
−40°C (−40°F)?
Is the voltage more than 10
V?
Is the voltage more than 10
V?
EN-119
Check Yes
Go to step 2.
Repair battery
short circuit in
harness between
intake air tem-
perature and
pressure sensor
and ECM connec-
tor.
Repair battery
short circuit in
harness between
intake air tem-
perature and
pressure sensor
and ECM connec-
tor.
Engine (Diagnostics)
No
Repair poor con-
tact.
NOTE:
In this case,
repair the follow-
ing:
¼ Poor contact in
intake air tem-
perature and
pressure sensor
¼ Poor contact in
ECM
¼ Poor contact in
coupling connec-
tor (B21)
¼ Poor contact in
joint connector
(B83)
Go to step 3.
Go to step 4.