Subaru 2009 IMPREZA Service Manual page 1489

Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step
1 CHECK HARNESS BETWEEN ECM AND
SECONDARY AIR PUMP RELAY CONNEC-
TOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from the ECM
and secondary air pump relay.
3) Measure the voltage between ECM and
chassis ground.
Connector & terminal
(B136) No. 8 (+) — Chassis ground (–):
Check
Is the voltage 10 V or more?
EN(H4DOTC)(diag)-268
Yes No
Repair the short Even if DTC is
circuit to power in detected, the cir-
the harness cuit has returned to
between ECM and a normal condition
secondary air at this time. Repro-
pump relay con- duce the failure,
nector. and then perform
the diagnosis
again.
NOTE:
In this case, tem-
porary poor con-
tact of connector
may be the cause.