Subaru Legacy III (2000-2003 year). Manual - part 1010

IM-24

IMMOBILIZER (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH TROUBLE CODE (DTC)

D: DTC P0153 INCORRECT IMMOBILIZER KEY (USE OF UNREGISTERED KEY)

DIAGNOSIS:
• Use of unregistered key in IMM ECM

Step

Value

Yes

No

1

PERFORM TEACHING OPERATION ON IG-
NITION KEY.
Perform teaching operation on all keys of the 
vehicle. Refer to teaching operation manual 
(Pub. No. S0820GZ).
Is teaching operation for all keys completed?

Teaching operation for all keys 
is completed.

END

Replace all ignition 
keys (including the 
transponder). Go 
to step 2.

2

PERFORM TEACHING OPERATION ON IG-
NITION KEY.
Perform teaching operation on all keys with 
vehicle. Refer to teaching operation manual 
(Pub. No. S0820GZ).
Is teaching operation for all keys completed?

Teaching operation for all keys 
is completed.

END

Replace IMM ECM  
<Ref. to SL-36, 
Immobilizer Con-
trol Module.> and 
then replace all 
ignition keys 
(including the tran-
sponder). Then 
perform teaching 
operation. Refer to 
teaching opera-
tion manual (Pub. 
No. S0820GZ).

IM-25

IMMOBILIZER (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH TROUBLE CODE (DTC)

E: DTC P1576 EGI CONTROL MODULE EEPROM

DIAGNOSIS:
• ECM malfunctioning

1. REPLACE ECM.

Replace ECM.
<Ref. to FU(H4SO)-45, Engine Control Module.>
<Ref. to FU(H4SOw/oOBD)-42, Engine Control Module.>
<Ref. to FU(H6DO)-46, Engine Control Module.>
<Ref. to FU(H4DOSTC)-40, Engine Control Module.>
Then perform teaching operation. Refer to teaching operation manual (Pub. No. S0820GZ).

F: DTC P1577 IMM CONTROL MODULE EEPROM

DIAGNOSIS:
• IMM ECM malfunctioning

1. REPLACE IMM ECM.

Replace IMM ECM  <Ref. to SL-36, Immobilizer Control Module.> and then replace all ignition keys (includ-
ing the transponder). Then perform teaching operation. Refer to teaching operation manual (Pub. No.
S0820GZ).

IM-26

IMMOBILIZER (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH TROUBLE CODE (DTC)

G: DTC P1570 ANTENNA

DIAGNOSIS:
• Faulty antenna
WIRING DIAGRAM:

IM-00066

2

1

B142

IMMOBILIZER

CONTROL

MODULE

ANTENNA

B142

1 2

IM-27

IMMOBILIZER (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE WITH TROUBLE CODE (DTC)

Step

Value

Yes

No

1

CHECK ANTENNA CIRCUIT.
1) Turn ignition switch OFF.
2) Disconnect harness antenna connector 

from IMM ECM.  <Ref. to SL-37, Immobi-
lizer Antenna.>

3) Measure resistance of antenna circuit.

Connector & terminal

(B142) No. 1 — No. 2:

Is the measured value less than the speci-
fied value?

10 

Ω

Go to step 2.

Replace antenna.  
<Ref. to SL-37, 
Immobilizer 
Antenna.>

2

CHECK ANTENNA CIRCUIT.
Measure resistance between antenna harness 
connector and chassis ground.

Connector & terminal

(B142) No. 1 — Chassis ground

Is the measured value less than the specified 
value?

10 

Ω

Replace antenna.  
<Ref. to SL-37, 
Immobilizer 
Antenna.>

Go to step 3.

3

CHECK ANTENNA CIRCUIT.
Measure resistance between antenna harness 
connector and chassis ground.

Connector & terminal

(B142) No. 2 — Chassis ground

Is the measured value less than the specified 
value?

10 

Ω

Replace antenna.  
<Ref. to SL-37, 
Immobilizer 
Antenna.>

Go to step 4.

4

CHECK ANTENNA CIRCUIT.
1) Turn ignition switch ON. (Engine OFF.)
2) Measure voltage between antenna harness 

connector and chassis ground.

Connector & terminal

(B142) No. 1 (+) — Chassis ground (

−−−−

):

Is the measured value same as the speci-
fied value?

0 V

Go to step 5.

Replace antenna.  
<Ref. to SL-37, 
Immobilizer 
Antenna.>

5

CHECK ANTENNA CIRCUIT.
Measure voltage between antenna harness 
connector and chassis ground.

Connector & terminal

(B142) No. 2 (+) — Chassis ground (

−−−−

):

Is the measured value same as the specified 
value?

0 V

Go to step 6.

Replace antenna.  
<Ref. to SL-37, 
Immobilizer 
Antenna.>

6

CHECK IMM ECM FUNCTION.
1) Turn ignition switch OFF.
2) Connect antenna harness connector to 

IMM ECM.

3) Insert the key to ignition switch, measure 

changes in voltage between antenna har-
ness connector terminals.

Connector & terminal

(B142) No. 1 (+) — No. 2 (

−−−−

):

Is the measured value same as the speci-
fied value?

−

30 to 30 V (Approximately 0.1 

second after inserting the key.) 
0 V (Approximately 1 second 
after inserting the key.)

Go to step 7.

Replace IMM ECM  
<Ref. to SL-36, 
Immobilizer Con-
trol Module.> and 
then replace all 
ignition keys 
(including the tran-
sponder). Then 
perform teaching 
operation. Refer to 
teaching opera-
tion manual (Pub. 
No. S0820GZ).