Subaru 2009 IMPREZA Service Manual page 1504

Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step
23 CHECK HARNESS BETWEEN ECM AND
ELECTRONIC THROTTLE CONTROL RE-
LAY CONNECTOR.
1) Turn the ignition switch to OFF.
2) Measure the resistance between electronic
throttle control relay connector and chassis
ground.
Connector & terminal
(B220) No. 32 — Chassis ground:
(B220) No. 30 — Chassis ground:
24 CHECK HARNESS BETWEEN ECM AND
ELECTRONIC THROTTLE CONTROL RE-
LAY CONNECTOR.
Measure the resistance between ECM and
electronic throttle control relay connector.
Connector & terminal
(B136) No. 21 — (B220) No. 32:
(B136) No. 1 — (B220) No. 30:
25 CHECK HARNESS BETWEEN ECM AND
ELECTRONIC THROTTLE CONTROL CON-
NECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from ECM and
electronic throttle control.
3) Measure the resistance between ECM and
chassis ground.
Connector & terminal
(B134) No. 19 — Chassis ground:
(B134) No. 18 — Chassis ground:
(B134) No. 18 — (B136) No. 6:
(B134) No. 28 — Chassis ground:
26 CHECK SHORT CIRCUIT INSIDE THE ECM.
1) Connect the connector to ECM.
2) Measure the resistance between electronic
throttle control connector and engine ground.
Connector & terminal
(B57) No. 6 — Engine ground:
(B57) No. 4 — Engine ground:
27 CHECK HARNESS BETWEEN ECM AND
ELECTRONIC THROTTLE CONTROL CON-
NECTOR.
1) Disconnect the connectors from ECM.
2) Measure the resistance of harness between
ECM and electronic throttle control connector.
Connector & terminal
(B134) No. 18 — (E57) No. 6:
(B134) No. 28 — (E57) No. 4:
(B134) No. 29 — (E57) No. 3:
Check
Is the resistance 1 M or
more?
Is the resistance less than 1 ? Go to step 25.
Is the resistance 1 M or
more?
Is the resistance 1 M or
more?
Is the resistance less than 1 ? Go to step 28.
EN(H4DOTC)(diag)-283
ENGINE (DIAGNOSTICS)
Yes No
Go to step 24. Repair the short
circuit in harness
to ground between
ECM and elec-
tronic throttle con-
trol relay
connector.
Repair the open
circuit in harness
between ECM and
electronic throttle
control relay con-
nector.
Go to step 26. Repair the short
circuit to ground in
harness between
ECM and elec-
tronic throttle con-
trol connector.
Go to step 27. Repair the short
circuit to ground in
harness between
ECM and elec-
tronic throttle con-
trol connector.
Replace the ECM if
defective. <Ref. to
FU(H4DOTC)-52,
Engine Control
Module (ECM).>
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