Subaru Legacy 2003 Service Manual page 1919

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)
ENGINE (DIAGNOSTICS)
5 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 and mass air flow sensor
connector.
Connector & terminal
(B84) No. 13 — (B3) No. 3:
(B135) No. 27 — (B3) No. 4:
(B135) No. 19 — (B3) No. 5:
Is the measured value less than the speci-
fied value?
6 CHECK HARNESS BETWEEN ECM AND
MASS AIR FLOW SENSOR CONNECTOR
Measure the resistance of harness between
ECM and chassis ground.
Connector & terminal
(B84) No. 13 — Chassis ground:
(B135) No. 27 — Chassis ground:
(B135) No. 19 — Chassis ground:
Does the measured value exceed the specified
value?
7 CHECK POOR CONTACT
Check poor contact in mass air flow sensor
connector.
Is there poor contact in mass air flow sensor
connector?
Step
EN(H4DOSTC)-80
Value
1Ω
1MΩ
There is poor contact.
Yes
Go to step 6. Repair the open
circuit between
ECM and mass air
flow sensor con-
nector.
Go to step 7. Repair the ground
short circuit
between ECM and
mass air flow sen-
sor connector.
Repair the poor Replace the mass
contact in mass air air flow and intake
flow sensor con- air temperature
nector. sensor. <Ref. to
FU(H4DOSTC)-
33, Mass Air Flow
and Intake Air
Temperature Sen-
sor.>
No