Subaru FORESTER 2001 Service Manual page 128

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(DOHC TURBO)-36, 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 MASS AIR
FLOW AND INTAKE AIR TEMPERATURE
SENSOR AND ECM CONNECTOR.
1) Turn ignition switch to OFF.
2) Disconnect connector from mass air flow
and intake air temperature sensor.
3) Measure voltage between mass air flow
and intake air temperature sensor connector
and engine ground.
Connector & terminal
(B3) 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 mass air flow
and intake air temperature sensor connector
and engine ground.
Connector & terminal
(B3) No. 2 (+) — Engine ground (−):
4 CHECK HARNESS BETWEEN MASS AIR
FLOW AND INTAKE AIR TEMPERATURE
SENSOR AND ECM CONNECTOR.
Measure voltage between mass air flow and
intake air temperature sensor and pressure
sensor connector and engine ground.
Connector & terminal
(B3) No. 2 (+) — Engine ground (−):
Step
Is the value less than
−36°C (−33°F)?
Is the voltage more than 10
V?
Is the voltage more than 10
V?
Is the voltage more than 3
V?
EN(DOHC TURBO)-127
Check Yes
Go to step 2.
Repair battery
short circuit in
harness between
mass air flow and
intake air tem-
perature sensor
and ECM connec-
tor.
Repair battery
short circuit in
harness between
mass air flow and
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
mass air flow and
intake air tem-
perature sensor
¼ Poor contact in
ECM
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
mass air flow and
intake air tem-
perature sensor
and ECM connec-
tor
¼ Poor contact in
mass air flow and
intake air tem-
perature sensor
¼ Poor contact in
ECM
¼ Poor contact in
joint connector