Subaru Legacy 2003 Service Manual page 2048

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
(B136) No. 1 (+) — Chassis ground ( − − − − ):
Does the measured value exceed the spec-
ified value?
2 CHECK POOR CONTACT.
Check the poor contact in ECM connector.
Is there poor contact in ECM connector?
3 CHECK HARNESS BETWEEN EXHAUST
VALVE CONTROL SOLENOID VALVE (POS-
ITIVE PRESSURE) AND ECM CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from exhaust
valve control solenoid valve (positive pres-
sure).
3) Turn the ignition switch to ON.
4) Measure the voltage between ECM and
chassis ground.
Connector & terminal
(B136) No. 1 (+) — Chassis ground ( − − − − ):
Does the measured value exceed the spec-
ified value?
4 CHECK EXHAUST VALVE CONTROL SOLE-
NOID VALVE (POSITIVE PRESSURE).
1) Turn the ignition switch to OFF.
2) Measure the resistance between exhaust
valve control solenoid valve (positive pres-
sure) terminals.
Terminals
No. 7 — No. 8:
Is the measured value less than the speci-
fied value?
5 CHECK POOR CONTACT.
Check poor contact in ECM and exhaust valve
control solenoid valve (positive pressure).
Is there poor contact in ECM and exhaust
valve control solenoid valve (positive pres-
sure)?
Value
10 V
There is poor contact.
10 V
1 Ω
There is poor contact.
EN(H4DOSTC)-209
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 exhaust
valve control sole-
noid valve (posi-
tive pressure)
connector. After
repair, replace the
ECM. <Ref. to
FU(H4DOSTC)-
40, Engine Con-
trol Module.>
Replace the Go to step 5.
exhaust valve con-
trol solenoid valve
(positive pres-
sure). <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 exhaust valve FU(H4DOSTC)-
control solenoid 40, Engine Con-
valve (positive trol Module.>
pressure).
No