Subaru Legacy 2002 Service Manual page 1338

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)
No.
1 CHECK CURRENT DATA.
1) Turn ignition switch to ON.
2) Start engine.
3) 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(H6)-38, 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 SENSOR AND ECM CON-
NECTOR.
1) Turn ignition switch to OFF.
2) Disconnect connector from intake air tem-
perature sensor.
3) Measure voltage between intake air tem-
perature sensor connector and engine
ground.
Connector & terminal
(E20) No. 1 (+) — Engine ground (−):
3 CHECK HARNESS BETWEEN INTAKE AIR
TEMPERATURE SENSOR AND ECM CON-
NECTOR.
1) Turn ignition switch to ON.
2) Measure voltage between intake air tem-
perature sensor connector and engine
ground.
Connector & terminal
(E20) No. 1 (+) — Engine ground (−):
4 CHECK HARNESS BETWEEN INTAKE AIR
TEMPERATURE SENSOR AND ECM CON-
NECTOR.
Measure voltage between intake air tempera-
ture sensor connector and engine ground.
Connector & terminal
(E20) No. 1 (+) — 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?
Is the voltage less than 4.7
V?
EN(H6)-131
Check Yes
Go to step 2.
Repair battery
short circuit in
harness between
intake air tem-
perature sensor
and ECM connec-
tor.
Repair battery
short circuit in
harness between
intake air tem-
perature sensor
and ECM connec-
tor.
Go to step 5.
Engine (DIAGNOSTICS)
No
Repair poor con-
tact.
NOTE:
In this case,
repair the follow-
ing:
¼ Poor contact in
intake air tem-
perature sensor
¼ Poor contact in
ECM
¼ Poor contact in
coupling connec-
tor
¼ Poor contact in
joint connector
Go to step 3.
Go to step 4.
Repair harness
and connector.
NOTE:
In this case,
repair the follow-
ing:
¼ Open circuit in
harness between
intake air tem-
perature sensor
and ECM connec-
tor
¼ Poor contact in
intake air tem-
perature sensor
¼ Poor contact in
ECM
¼ Poor contact in
coupling connec-
tor
¼ Poor contact in
joint connector