Subaru IMPREZA 2004 Service Manual page 769

Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step
1 CHECK INTAKE AIR TEMPERATURE SEN-
SOR.
1)Turn the ignition switch to OFF.
2)Disconnect the connector from intake air
temperature sensor.
3)Measure the resistance between intake air
temperature sensor terminals.
Terminals
No. 2 — No. 3:
2 CHECK INTAKE AIR TEMPERATURE SEN-
SOR.
Measure the resistance between intake air
temperature sensor terminals.
Terminals
No. 2 — No. 3:
3 CHECK HARNESS BETWEEN ECM AND IN-
TAKE AIR TEMPERATURE SENSOR CON-
NECTOR.
1)Disconnect the connector from ECM.
2)Measure the resistance of harness connec-
tor between ECM and intake air temperature
sensor connector.
Connector & terminal
(B136) No. 15 — (E20) No. 3:
4 CHECK HARNESS BETWEEN ECM AND IN-
TAKE AIR TEMPERATURE SENSOR CON-
NECTOR.
Measure the resistance of harness connector
between ECM and intake air temperature sen-
sor connector.
Connector & terminal
(B136) No. 13 — (E20) No. 2:
5 CHECK HARNESS BETWEEN ECM AND IN-
TAKE AIR TEMPERATURE SENSOR CON-
NECTOR.
Measure the resistance of harness between
ECM connector and chassis ground.
Connector & terminal
(B136) No. 15 — Chassis ground:
6 CHECK HARNESS BETWEEN ECM AND IN-
TAKE AIR TEMPERATURE SENSOR CON-
NECTOR.
Measure the resistance of harness between
ECM connector and chassis ground.
Connector & terminal
(B136) No. 13 — Chassis ground:
Is the resistance 2 — 3 kΩ at
20°C (68°F)?
Is the resistance 0.66 — 1 kΩ
at 50°C (122°F)?
Is the resistance less than 1
Ω?
Is the resistance less than 1
Ω?
Is the resistance more than 1
MΩ?
Is the resistance more than 1
MΩ?
EN(H4SOw/oOBD)(diag)-73
Check
Go to step 2.
Go to step 3.
Go to step 4.
Go to step 5.
Go to step 6.
Go to step 7.
ENGINE (DIAGNOSTICS)
Yes No
Replace the intake
air temperature
sensor. <Ref. to
FU(H4SOw/
oOBD)-34, Intake
Air Temperature
and Manifold
Absolute Pres-
sure Sensor.>
Replace the intake
air temperature
sensor. <Ref. to
FU(H4SOw/
oOBD)-34, Intake
Air Temperature
and Manifold
Absolute Pres-
sure Sensor.>
Repair the har-
ness and connec-
tor.
NOTE:
In this case, repair
the following:
• Open circuit in
harness between
ECM and intake
air temperature
and manifold
absolute pressure
sensor connector
• Poor contact in
coupling connector
(B21)
Repair the har-
ness and connec-
tor.
Repair the ground
short circuit in har-
ness between
ECM and idle air
control solenoid
valve connector.
Repair the ground
short circuit in har-
ness between
ECM and idle air
control solenoid
valve connector.