Subaru LEGACY 2003 Service Manual page 79

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)
Step
1 CHECK INTAKE AIR TEMPERATURE SEN-
SOR.
1) Turn ignition switch to OFF.
2) Disconnect connector from intake air tem-
perature sensor.
3) Measure resistance between intake air
temperature sensor terminals.
Terminals
No. 2 — No. 3:
Is resistance within the specified value at
20°C (68°F)?
2 CHECK INTAKE AIR TEMPERATURE SEN-
SOR.
Measure resistance between intake air tem-
perature sensor terminals.
Terminals
No. 2 — No. 3:
Is resistance within the specified value at 50°C
(122°F)?
3 CHECK HARNESS BETWEEN ECM AND IN-
TAKE AIR TEMPERATURE SENSOR CON-
NECTOR.
1) Disconnect connector from ECM.
2) Measure resistance of harness connector
between ECM and intake air temperature
sensor connector.
Connector & terminal
(B136) No. 15 — (E20) No. 3:
Is the measured value less than the speci-
fied value?
4 CHECK HARNESS BETWEEN ECM AND IN-
TAKE AIR TEMPERATURE SENSOR CON-
NECTOR.
Measure resistance of harness connector
between ECM and intake air temperature sen-
sor connector.
Connector & terminal
(B136) No. 13 — (E21) No. 2:
Is the measured value less than the specified
value?
5 CHECK HARNESS BETWEEN ECM AND IN-
TAKE AIR TEMPERATURE SENSOR CON-
NECTOR.
Measure resistance of harness between ECM
connector and chassis ground.
Connector & terminal
(B136) No. 15 — Chassis ground:
Does the measured value exceed the specified
value?
Value
2 — 3 kΩ
0.66 — 1 kΩ
1 Ω
1 Ω
1 MΩ
EN(H4SOw/oOBD)-77
ENGINE (DIAGNOSTICS)
Yes
Go to step 2. Replace intake air
temperature sen-
sor. <Ref. to
FU(H4SOw/
oOBD)-32, Intake
Air Temperature
and Pressure Sen-
sor.>
Go to step 3. Replace intake air
temperature sen-
sor. <Ref. to
FU(H4SOw/
oOBD)-32, Intake
Air Temperature
and Pressure Sen-
sor.>
Go to step 4. Repair harness
and connector.
NOTE:
In this case, repair
the following:
• Open circuit in
harness between
ECM and intake
air temperature
and pressure sen-
sor connector
• Poor contact in
coupling connector
(B21)
Go to step 5. Repair harness
and connector.
Go to step 6. Repair ground
short circuit in har-
ness between
ECM and idle air
control solenoid
valve connector.
No