Subaru Impreza 2004 Service Manual page 74

Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step
1 CHECK OUTPUT SIGNAL FROM ECM.
1)Turn the ignition switch to ON.
2)Measure the voltage between ECM and
chassis ground.
Connector & terminal
(B84) No. 24 (+) — Chassis ground ( − − − − ):
2 CHECK HARNESS BETWEEN WASTEGATE
CONTROL SOLENOID VALVE AND ECM
CONNECTOR.
1)Turn the ignition switch to OFF.
2)Disconnect the connectors from wastegate
control solenoid valve and ECM.
3)Measure the resistance of harness between
wastegate control solenoid valve connector
and engine ground.
Connector & terminal
(B127) No. 1 — Engine ground:
3 CHECK HARNESS BETWEEN WASTEGATE
CONTROL SOLENOID VALVE AND ECM
CONNECTOR.
Measure the resistance of harness between
ECM and wastegate control solenoid valve of
harness connector.
Connector & terminal
(B84) No. 24 — (B127) No. 1:
4 CHECK WASTEGATE CONTROL SOLE-
NOID VALVE.
1)Remove the wastegate control solenoid
valve.
2)Measure the resistance between wastegate
control solenoid valve terminals.
Terminals
No. 1 — No. 2:
5 CHECK POWER SUPPLY TO WASTEGATE
CONTROL SOLENOID VALVE.
1)Turn the ignition switch to ON.
2)Measure the voltage between wastegate
control solenoid valve and engine ground.
Connector & terminal
(B127) No. 2 (+) — Engine ground ( − − − − ):
6 CHECK POOR CONTACT.
Check poor contact in wastegate control sole-
noid valve connector.
Check
Is the voltage more than 10 V? Even if malfunction
Is the resistance less than 10
Ω?
Is the resistance less than 1
Ω?
Is the resistance 30 — 40 Ω?
Is the voltage more than 10 V? Go to step 6.
Is there poor contact in waste-
gate control solenoid valve
connector?
EN(H4DOTC)(diag)-153
ENGINE (DIAGNOSTICS)
Yes
Go to step 2.
indicator light
lights up, the cir-
cuit has returned
to a normal condi-
tion at this time.
Repair the ground Go to step 3.
short circuit in har-
ness between
ECM and waste-
gate control sole-
noid valve
connector.
Go to step 4. Repair the open
circuit in harness
between ECM and
wastegate control
solenoid valve
connector.
NOTE:
In this case, repair
the following:
• Open circuit in
harness between
ECM and waste-
gate control sole-
noid valve
connector
Go to step 5. Replace the
wastegate control
solenoid valve.
<Ref. to
FU(H4DOTC)-43,
Wastegate Con-
trol Solenoid
Valve.>
Repair the open
circuit in harness
between main
relay and waste-
gate control sole-
noid valve
connector.
Repair the poor Contact your Sub-
contact in waste- aru distributor ser-
gate control sole- vice.
noid valve
NOTE:
connector.
Inspection by DTM
is required,
cause
cause is deteriora-
tion of
parts.
No
be-
probable
multiple