Subaru Legacy 2005 Service Manual page 1320

Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step
1 READ DATA CONNECTING SUBARU SE-
LECT MONITOR.
1) Turn the ignition switch to OFF.
2) Connect the Subaru Select Monitor or gen-
eral scan tool to data link connector.
3) Turn the ignition switch to ON.
4) Start and idle the engine.
5) Read the voltage of mass air flow sensor
using Subaru Select Monitor.
NOTE:
• Subaru Select Monitor
For detailed operation procedure, refer to
"READ CURRENT DATA FOR ENGINE". <Ref.
to EN(H4DOTC)(diag)-24, Subaru Select Mon-
itor.>
• General scan tool
For detailed operation procedure, refer to the
general scan tool operation manual.
2 CHECK HARNESS BETWEEN ECM AND
MASS AIR FLOW SENSOR CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from mass air-
flow sensor.
3) Turn the ignition switch to ON.
4) Measure the voltage between mass air flow
sensor connector and chassis ground.
Connector & terminal
(B3) No. 3 (+) — Chassis ground (
3 CHECK HARNESS BETWEEN ECM AND
MASS AIR FLOW SENSOR CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Measure the resistance of harness
between ECM connector and mass air flow
sensor connector.
Connector & terminal
(B3) No. 2 — (B136) No. 31:
Check
Is the voltage 0.2 — 4.7 V?
Is the voltage more than 5 V?
−
):
Is the resistance less than 1
Ω?
EN(H4DOTC)(diag)-80
Yes
Even if the mal- Go to step 2.
function indicator
light illuminates,
the circuit has
returned to a nor-
mal condition at
this time.
Repair the battery Go to step 3.
short circuit of har-
ness between
mass air flow sen-
sor connector and
ECM connector.
Replace the mass Repair the open
air flow sensor. circuit of harness
<Ref. to between mass air
FU(H4DOTC)-27, flow sensor con-
Mass Air Flow and nector and ECM
Intake Air Temper- connector.
ature Sensor.>
No