Subaru Legacy 2003 Service Manual page 2042

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)
Step
1 CHECK INPUT SIGNAL TO ECM.
1) Turn the ignition switch to ON.
2) Measure the voltage between ECM and
chassis ground.
Connector & terminal
(B137) No. 22 (+) — Chassis ground ( − − − − ):
Does the measured value exceed the spec-
ified value?
2 CHECK POOR CONTACT.
Check poor contact in ECM connector.
Is there poor contact in ECM connector?
3 CHECK HARNESS BETWEEN INTAKE AIR
VALVE CONTROL SOLENOID VALVE AND
ECM CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from intake air
valve control solenoid valve.
3) Turn the ignition switch to ON.
4) Measure the voltage between ECM and
chassis ground.
Connector & terminal
(B137) No. 12 (+) — Chassis ground ( − − − − ):
Does the measured value exceed the spec-
ified value?
4 CHECK INTAKE AIR VALVE CONTROL SO-
LENOID VALVE.
1) Turn the ignition switch to OFF.
2) Measure the resistance between intake air
valve control solenoid valve terminals.
Terminals
No. 9 — No. 10:
Is the measured value less than the speci-
fied value?
5 CHECK POOR CONTACT.
Check poor contact in ECM and intake air
valve control solenoid valve connectors.
Is there poor contact in ECM and intake air
valve control solenoid valve connectors?
Value
10 V
There is poor contact.
10 V
1 Ω
There is poor contact.
EN(H4DOSTC)-203
ENGINE (DIAGNOSTICS)
Yes
Go to step 3. Go to step 2.
Repair the poor Replace the ECM.
contact in ECM <Ref. to
connector. FU(H4DOSTC)-
40, Engine Con-
trol Module.>
Repair the battery Go to step 4.
short circuit in har-
ness between
ECM and intake
air valve control
solenoid valve
connector. After
repair, replace the
ECM. <Ref. to
FU(H4DOSTC)-
40, Engine Con-
trol Module.>
Replace the intake Go to step 5.
air valve control
solenoid valve
<Ref. to
IN(H4DOSTC)-19,
Solenoid Box
Assembly.> and
ECM. <Ref. to
FU(H4DOSTC)-
40, Engine Con-
trol Module.>
Repair the poor Replace the ECM.
contact in ECM <Ref. to
and intake air FU(H4DOSTC)-
valve control sole- 40, Engine Con-
noid valve connec- trol Module.>
tors.
No