Subaru IMPREZA 2004 Service Manual page 16

Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step
1 CHECK OUTPUT SIGNAL FROM ECM.
1)Turn ignition switch to ON.
2)Measure voltage between ECM and chassis
ground.
Connector & terminal
(B134) No. 12 (+) — Chassis ground ( − − − − ):
2 CHECK POWER SUPPLY TO AIR ASSIST IN-
JECTOR SOLENOID VALVE.
1)Turn ignition switch to OFF.
2)Disconnect connector from air assist injector
solenoid valve.
3)Turn ignition switch to ON.
4)Measure voltage between air assist injector
solenoid valve and engine ground.
Connector & terminal
(E42) No. 2 (+) — Engine ground ( − − − − ):
3 CHECK HARNESS BETWEEN ECM AND AIR
ASSIST INJECTOR SOLENOID VALVE CON-
NECTOR.
1)Turn ignition switch to OFF.
2)Disconnect connector from ECM.
3)Measure resistance of harness between
ECM and air assist injector solenoid valve con-
nector.
Connector & terminal
(B134) No. 12— (E42) No. 1:
4 CHECK HARNESS BETWEEN ECM AND AIR
ASSIST INJECTOR SOLENOID VALVE CON-
NECTOR.
Measure resistance of harness between ECM
and chassis ground.
Connector & terminal
(B134) No. 12— Chassis ground:
5 CHECK POOR CONTACT.
Check poor contact in ECM and air assist
injector solenoid valve connectors.
Check
Is the voltage more than 10 V? Repair poor con-
Is the voltage more than 10 V? Go to step 3.
Is the resistance less than 1
Ω?
Is the resistance more than 1
MΩ?
Is there poor contact in ECM
and air assist injector solenoid
valve connectors?
EN(H4SO)(diag)-93
ENGINE (DIAGNOSTICS)
Yes
Go to step 2.
tact in ECM con-
nector.
Repair harness
and connector.
NOTE:
In this case, repair
the following:
• Open circuit in
harness between
air assist injector
solenoid valve and
main relay connec-
tor
• Poor contact in
coupling connector
Go to step 4. Repair harness
and connector.
NOTE:
In this case, repair
the following:
• Open circuit in
harness between
ECM and air assist
injector solenoid
valve connector
• Poor contact in
coupling connector
Go to step 5. Repair ground
short circuit in har-
ness between
ECM and air assist
injector solenoid
valve connector.
Repair poor con- Replace air assist
tact in ECM and injector solenoid
air assist injector valve. <Ref. to
solenoid valve FU(H4SO)-37, Air
connectors. Assist Injector
Solenoid Valve.>
No