Subaru Impreza 2003 Service Manual page 3299

DIAGNOSTICS CHART WITH DIAGNOSTIC TROUBLE CODE (DTC)
Step
6 CHECK HARNESS OF COMMUNICATION
LINE.
1)Turn the ignition switch to ON. (Engine
OFF.)
2)Measure the voltage between IMM ECM har-
ness connector terminal and chassis ground.
Connector & terminal
(B141) No. 1, No.6 (+) — Chassis ground
( − − − − ):
7 CHECK HARNESS OF COMMUNICATION
LINE.
Measure the voltage between ECM harness
connector terminal and engine ground.
Connector & terminal
LHD SOHC and RHD SOHC model with
OBD
(B137) No. 17, No. 18 (+) — Engine
ground ( − − − − ):
RHD SOHC model without OBD
(B135) No. 22, No.23 (+) — Engine
ground ( − − − − ):
Turbo model
(B135) No. 5, No.14 (+) — Engine
ground ( − − − − ):
8 CHECK ECM BY INTERFACE CHECK.
1)Connect the harness connector to ECM.
2)Disconnect the harness connector from IMM
ECM.
3)Perform interface check. <Ref. to IM-7,
INTERFACE CHECK, Subaru Select Monitor.>
Check
Is the voltage 0 V?
Is the voltage 0 V?
Does "Commun. Line Shorted
to Ground" appear on the
screen?
IM-21
IMMOBILIZER (DIAGNOSTICS)
Yes
Go to step 7. Repair the har-
ness between IMM
ECM and ECM,
because there is
short circuit with
battery voltage line
or ignition switch
"ON" line.
Go to step 8. Repair the har-
ness between IMM
ECM and ECM,
because there is
short circuit with
battery voltage line
or ignition switch
"ON" line.
Replace the ECM. Go to step 9.
<Ref. to
FU(H4SO)-48,
Engine Control
Module (ECM).>,
<Ref. to
FU(H4SOw/
oOBD)-43, Engine
Control Module
(ECM).> or <Ref.
to FU(H4DOTC)-
49, Engine Con-
trol Module
(ECM).> Then per-
form teaching
operation. Refer to
the teaching oper-
ation manual (Pub.
No. S0820GZ).
No