Subaru 2009 IMPREZA Service Manual page 557

Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step
1 CHECK HARNESS BETWEEN ECM AND
ELECTRONIC THROTTLE CONTROL.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from ECM and
electronic throttle control.
3) Measure the resistance of harness between
ECM and electronic throttle control connector.
Connector & terminal
(B134) No. 18 — (E57) No. 6:
(B134) No. 29 — (E57) No. 3:
2 CHECK HARNESS BETWEEN ECM AND
ELECTRONIC THROTTLE CONTROL.
1) Connect the connector to ECM.
2) Measure the resistance between electronic
throttle control connector and engine ground.
Connector & terminal
(E57) No. 3 — Engine ground:
3 CHECK HARNESS BETWEEN ECM AND
ELECTRONIC THROTTLE CONTROL.
1) Turn the ignition switch to ON.
2) Measure the voltage between electronic
throttle control connector and engine ground.
Connector & terminal
(E57) No. 6 (+) — Engine ground (–):
4 CHECK HARNESS BETWEEN ECM AND
ELECTRONIC THROTTLE CONTROL.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from ECM.
3) Measure the resistance between ECM con-
nectors.
Connector & terminal
(B134) No. 19 — (B134) No. 18:
Check
Is the resistance less than 1 ? Go to step 2.
Is the resistance less than 5 ? Go to step 3.
Is the voltage 4.85 V or more? Repair the short
Is the resistance 1 M or
more?
EN(H4SO)(diag)-140
Yes No
Repair the harness
and connector.
NOTE:
In this case, repair
the following item:
• Open circuit in
harness between
ECM and electron-
ic throttle control
connector
• Poor contact of
coupling connector
Repair the harness
and connector.
NOTE:
In this case, repair
the following item:
• Open circuit of
harness between
ECM and engine
ground
• Poor contact of
ECM connector
• Poor contact of
coupling connector
Go to step 4.
circuit to power in
harness between
ECM and elec-
tronic throttle con-
trol connector.
Repair the poor Repair the short
contact of elec- circuit to power in
tronic throttle con- harness between
trol connector. ECM and elec-
Replace the elec- tronic throttle con-
tronic throttle con- trol connector.
trol if defective.
<Ref. to
FU(H4SO)-14,
Throttle Body.>