Subaru 2009 IMPREZA Service Manual page 683

Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step
1 CHECK INPUT SIGNAL OF ECM.
1) Turn the ignition switch to OFF.
2) Measure the voltage between ECM and
chassis ground.
Connector & terminal
(B135) No. 5 (+) — Chassis ground (–):
2 CHECK HARNESS BETWEEN ECM AND
MAIN FUSE BOX CONNECTOR.
1) Disconnect the connectors from ECM.
2) Measure the resistance between ECM and
chassis ground.
Connector & terminal
(B135) No. 5 — Chassis ground:
3 CHECK FUSE NO. 13 (MAIN FUSE BOX).
Check
Is the voltage 10 V or more?
Is the resistance 1 M or
more?
Is the fuse blown out?
EN(H4SO)(diag)-266
Yes No
Repair the poor Go to step 2.
contact of ECM
connector.
Go to step 3. Repair the ground
short circuit of har-
ness between
ECM and battery
terminal.
Replace the fuse. Repair the harness
and connector.
NOTE:
In this case, repair
the following item:
• Open circuit in
harness between
ECM and battery
• Poor contact of
ECM connector
• Poor contact of
battery terminal