Subaru 2009 IMPREZA Service Manual page 1571

Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step
1 CHECK CURRENT DATA.
1) Turn the ignition switch to ON.
2) Read the data of secondary air piping pres-
sure signal using Subaru Select Monitor or gen-
eral scan tool.
NOTE:
• Subaru Select Monitor
For detailed operation procedures, refer to
"READ CURRENT DATA FOR ENGINE". <Ref.
to EN(H4DOTC)(diag)-34, Subaru Select Moni-
tor.>
• General scan tool
For detailed operation procedures, refer to the
general scan tool operation manual.
2 CHECK POWER SUPPLY OF SECONDARY
AIR COMBINATION VALVE RH.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from the second-
ary air combination valve RH.
3) Turn the ignition switch to ON.
4) Measure the voltage between the second-
ary air combination valve RH connector and
chassis ground.
Connector & terminal
(E41) No. 1 (+) — Chassis ground (–):
3 CHECK HARNESS BETWEEN ECM AND
SECONDARY AIR COMBINATION VALVE
RH CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from ECM.
3) Measure the resistance of the harness
between the ECM and secondary air combina-
tion valve RH connector.
Connector & terminal
(B134) No. 27 — (E41) No. 2:
4 CHECK HARNESS BETWEEN ECM AND
SECONDARY AIR COMBINATION VALVE
RH CONNECTOR.
Measure the resistance between ECM and
chassis ground.
Connector & terminal
(B134) No. 27 — Chassis ground:
5 CHECK POOR CONTACT.
Check for poor contact of ECM and secondary
air combination valve RH connector.
Check
Is the measured value less than
53.3 kPa (400 mmHg,
15.8 inHg)?
Is the voltage 4.5 V or more?
Is the resistance less than 1 ? Go to step 4.
Is the resistance 1 M or
more?
Is there poor contact of ECM or
secondary air combination
valve RH connector?
EN(H4DOTC)(diag)-350
Yes No
Go to step 2. Even if DTC is
detected, the cir-
cuit has returned to
a normal condition
at this time. Repro-
duce the failure,
and then perform
the diagnosis
again.
NOTE:
In this case, tem-
porary poor con-
tact of connector
may be the cause.
Go to step 3. Repair the harness
and connector.
NOTE:
In this case, repair
the following item:
• Open circuit in
harness between
ECM and second-
ary air combination
valve RH connec-
tor
• Poor contact of
ECM connector
• Poor contact of
coupling connector
Repair the harness
and connector.
NOTE:
In this case, repair
the following item:
• Open circuit in
harness between
ECM and second-
ary air combination
valve RH connec-
tor
• Poor contact of
coupling connector
Go to step 5. Repair the ground
short circuit of har-
ness between
ECM and second-
ary air combination
valve RH connec-
tor.
Repair the poor Replace the sec-
contact of ECM or ondary air combi-
secondary air com- nation valve RH.
bination valve RH <Ref. to
connector. EC(H4DOTC)-25,
Secondary Air
Combination
Valve.>