Subaru Legacy IV (2008 year). Manual - part 1166

IM(diag)-21

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

IMMOBILIZER (DIAGNOSTICS)

Step

Check

Yes

CHECK BODY INTEGRATED UNIT POWER
SUPPLY CIRCUIT.
1) Turn the ignition switch to OFF.
2) Disconnect the harness connector from
body integrated unit.
3) Measure the voltage between body inte-
grated unit harness connector terminal and
chassis ground.

Connector & terminal

(B280) No. 7 (+) — Chassis ground (–):
(B281) No. 2 (+) — Chassis ground (–):

Is the voltage 10 V or more?

Go to step 2.

Check the harness
for open or short
circuit between the
body integrated
unit and fuse.

CHECK BODY INTEGRATED UNIT POWER
SUPPLY CIRCUIT.
1) Turn the ignition switch to ON. (engine OFF)
2) Measure the voltage between body inte-
grated unit harness connector terminal and
chassis ground.

Connector & terminal

(i84) No. 1 (+) — Chassis ground (–):

Is the voltage 10 V or more?

Go to step 3.

Check the harness
for open or short
circuit between the
body integrated
unit and ignition
switch.

CHECK BODY INTEGRATED UNIT GROUND
CIRCUIT.
1) Turn the ignition switch to OFF.
2) Measure the resistance between body inte-
grated unit harness connector terminal and
chassis ground.

Connector & terminal

(B280) No. 22 — Chassis ground:
(B281) No. 8 — Chassis ground:
(B281) No. 9 — Chassis ground:

Is the resistance less than 10

:? Go to step 4.

Repair the open
circuit of body inte-
grated unit ground
circuit.

CHECK GROUND CIRCUIT FOR ECM.
Measure the resistance between the ECM
ground terminal and engine ground.

Is the resistance less than 10

:? Go to step 5.

Repair ground cir-
cuit of ECM.

CHECK HARNESS BETWEEN BODY INTE-
GRATED UNIT AND ECM.
1) Disconnect the harness connector from the
ECM and body integrated unit.
2) Measure the resistance between body inte-
grated unit harness connector terminal and
ECM harness connector terminal.

Connector & terminal

(B280) No. 18 — (B136) No. 26:

Is the resistance less than 10

:? Go to step 6.

Repair the open
circuit of the har-
ness between the
body integrated
unit and ECM.

CHECK HARNESS BETWEEN BODY INTE-
GRATED UNIT AND ECM.
Measure the resistance between body inte-
grated unit harness connector terminal and
ECM harness connector terminal.

Connector & terminal

(B280) No. 28 — (B136) No. 34:

Is the resistance less than 10

:? Go to step 7.

Repair the open
circuit of the har-
ness between the
body integrated
unit and ECM.

CHECK COMMUNICATION CIRCUIT HAR-
NESS.
1) Turn the ignition switch to ON. (engine OFF)
2) Measure the voltage between body inte-
grated unit harness connector terminal and
chassis ground.

Connector & terminal

(B280) No. 18 (+) — Chassis ground (–):
(B280) No. 28 (+) — Chassis ground (–):

Is the voltage 0 V?

Go to step 8.

Because the bat-
tery voltage or igni-
tion switch “ON”
circuit is shorted,
repair the harness
between the body
integrated unit and
ECM.

IM(diag)-22

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

IMMOBILIZER (DIAGNOSTICS)

CHECK COMMUNICATION CIRCUIT HAR-
NESS.
Measure voltage between the ECM harness
connector terminal and engine ground.

Connector & terminal

(B136) No. 26 (+) — Engine ground (–):
(B136) No. 34 (+) — Engine ground (–):

Is the voltage 0 V?

Go to step 9.

Because the bat-
tery voltage or igni-
tion switch “ON”
circuit is shorted,
repair the harness
between the body
integrated unit and
ECM.

CHECK ECM BY COMMUNICATION LINE
CHECK.
1) Connect the harness connector to ECM.
2) Disconnect the harness connector from
body integrated unit.
3) Start the communication line short check.
<Ref. to IM(diag)-7, COMMUNICATION LINE
CHECK, OPERATION, Subaru Select Moni-
tor.>

Is the communication line
check OK?

Replace the body
integrated unit
<Ref. to SL-56,
Body Integrated
Unit.> Replace all
ignition keys
(including the tran-
sponder). Execute
the registration
procedure next.
Refer to the “PC
application help for
Subaru Select
Monitor”.

Replace the ECM.
<Ref. to
FU(H4DOTC)-52,
Engine Control
Module (ECM).>
<Ref. to
FU(H6DO)-38,
Engine Control
Module (ECM).>
Perform the regis-
tration procedure
next. Refer to the
“PC application
help for Subaru
Select Monitor”.

Step

Check

Yes

IM(diag)-23

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

IMMOBILIZER (DIAGNOSTICS)

E: DTC P1574 KEY COMMUNICATION FAILURE

DTC DETECTING CONDITION:
Communication failure between key and body integrated unit

F: DTC P1576 EGI CONTROL MODULE EEPROM

DTC DETECTING CONDITION:
• ECM malfunctioning
• Inaccessible ROM in ECM during key registration.

Step

Check

Yes

CHECK BODY INTEGRATED UNIT FUNC-
TION.
Insert the key into the ignition switch (LOCK
position), then measure changes in voltage
between the antenna connectors.

Connector & terminal

(B351) No. 1 (+) — No. 2 (–):

Is the voltage –30 to 30 V?
(Approx. 0.1 second after
inserting the key) Is the voltage
0 V? (Approx. 1 second after
inserting the key)

Go to step 2.

CHECK IGNITION KEY (TRANSPONDER).
1) Remove the key from ignition switch.
2) Start the engine using other key which is
already registered.

Does the engine start?

Replace the igni-
tion key (including
the transponder).
Execute the regis-
tration procedure
next. Refer to the
“PC application
help for Subaru
Select Monitor”.

Step

Check

Yes

PERFORM REGISTRATION ON IGNITION
KEY.
Perform registration on all keys of the vehicle.
Refer to the “PC application help for Subaru
Select Monitor”.

Is registration for all keys com-
plete?

Verify that the
engine starts with
all registered keys
and finish the diag-
nosis.

Go to step 2.

PERFORM REGISTRATION ON IGNITION
KEY.
Perform registration on all keys of the vehicle.
Refer to the “PC application help for Subaru
Select Monitor”.

Is registration for all keys com-
plete?

Verify that the
engine starts with
all registered keys
and finish the diag-
nosis.

Go to step 3.

PERFORM REGISTRATION ON IGNITION
KEY.
Perform registration on all keys of the vehicle.
Refer to the “PC application help for Subaru
Select Monitor”.

Is registration for all keys com-
plete?

Verify that the
engine starts with
all registered keys
and finish the diag-
nosis.

Replace the ECM.
<Ref. to
FU(H4DOTC)-52,
Engine Control
Module (ECM).>
<Ref. to
FU(H6DO)-38,
Engine Control
Module (ECM).>

IM(diag)-24

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

IMMOBILIZER (DIAGNOSTICS)

G: DTC P1577 IMM CONTROL MODULE EEPROM

DTC DETECTING CONDITION:
• Body integrated unit malfunctioning
• Failed to access the ROM inside the body integrated unit.

H: DTC P1578 METER FAILURE

DTC DETECTING CONDITION:
Reference code incompatibility between combination meter and body integrated unit

Step

Check

Yes

PERFORM REGISTRATION ON IGNITION
KEY.
Perform registration on all keys of the vehicle.
Refer to the “PC application help for Subaru
Select Monitor”.

Is registration for all keys com-
plete?

Verify that the
engine starts with
all registered keys
and finish the diag-
nosis.

Go to step 2.

PERFORM REGISTRATION ON IGNITION
KEY.
Perform registration on all keys of the vehicle.
Refer to the “PC application help for Subaru
Select Monitor”.

Is registration for all keys com-
plete?

Verify that the
engine starts with
all registered keys
and finish the diag-
nosis.

Go to step 3.

PERFORM REGISTRATION ON IGNITION
KEY.
Perform registration on all keys of the vehicle.
Refer to the “PC application help for Subaru
Select Monitor”.

Is registration for all keys com-
plete?

Verify that the
engine starts with
all registered keys
and finish the diag-
nosis.

Replace the body
integrated unit.
<Ref. to SL-56,
Body Integrated
Unit.>

Step

Check

Yes

CHECK DIAGNOSTIC CODE.
Read the DTC of body integrated unit using
Subaru Select Monitor.

Is DTC B1401 detected?

Go to step 2.

<Ref. to IM(diag)-
20, DTC P1572
IMM CIRCUIT
FAILURE
(EXCEPT
ANTENNA CIR-
CUIT), Diagnostic
Procedure with
Diagnostic Trouble
Code (DTC).>

CHECK LAN COMMUNICATION SYSTEM.
Inspect LAN communication system. <Ref. to
LAN(diag)-2, Basic Diagnostic Procedure.>

Is DTC U1300, U1301, U1302,
B1100 or B1101 of the body
integrated unit displayed?

Perform the diag-
nosis according to
DTC. <Ref. to
LAN(diag)-31, List
of Diagnostic Trou-
ble Code (DTC).>

Go to step 3.

CHECK COMBINATION METER.
1) Perform the registration of immobilizer.
Refer to the “PC application help for Subaru
Select Monitor”.
2) Start the engine.

Does the engine start?

System is normal. Replace the com-

bination meter.
<Ref. to IDI-22,
REMOVAL, Com-
bination Meter.>

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