Subaru 2004 Forester, Service Manual

Page: 618 / 622

IM-18
IMMOBILIZER (DIAGNOSTIC)
Diagnostics Procedure with Diagnostic Trouble Code (DTC)
6 CHECK HARNESS OF COMMUNICATION
LINE.
1) Turn the ignition switch to ON. (engine
OFF.)
2) Measure the voltage between IMM ECM
harness connector terminal and chassis
ground.
Connector & terminal
(B141) No. 1, No. 6 (+) — Chassis ground
(
−
):
Is the voltage 0 V? 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.
7 CHECK HARNESS OF COMMUNICATION
LINE.
Measure the voltage between ECM harness
connector terminal and engine ground.
Connector & terminal
Non-turbo model
(B137) No. 17, No. 18 (+) — Engine
ground(
−
):
Turbo model
(B137) No. 19, No. 27 (+) — Engine
ground(
−
):
Is the voltage 0 V? 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.
8 CHECK ECM BY COMMUNICATION LINE
CHECK.
1) Connect the harness connector to ECM.
2) Disconnect the harness connector from
IMM ECM.
3) Perform communication line check. <Ref. to
IM-7, COMMUNICATION LINE CHECK,
OPERATION, Subaru Select Monitor.>
Does “Communication Line not
Shorted” appear on the
screen? Replace the IMM
ECM <Ref. to SL-
37, Immobilizer
Control Module.>
and then replace
all ignition keys
(including the tran-
sponder). Then
perform teaching
operation. Refer to
the teaching oper-
ation manual (Pub.
No. S0820GZ). Replace the ECM.
<Ref. to
FU(H4SO)-44,
Engine Control
Module (ECM).>
<Ref. to
FU(H4DOTC)-50,
Engine Control
Module (ECM).>
<Ref. to
FU(H4DOTC 2.5)-
41, Engine Con-
trol Module
(ECM).> Then per-
form teaching
operation. Refer to
the teaching oper-
ation manual (Pub.
No. S0820GZ).
Step Check Yes No