Subaru Legacy 2003 Service Manual page 29

DIAGNOSTIC PROCEDURE WITH TROUBLE CODE (DTC)
Step
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?
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?
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?
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?
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?
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?
Value
10 Ω
10 Ω
10 Ω
0 V
0 V
−30 to 30 V (Approximately 0.1
second after inserting the key.)
0 V (Approximately 1 second
after inserting the key.)
IM-27
IMMOBILIZER (DIAGNOSTICS)
Yes
Go to step 2. Replace antenna.
<Ref. to SL-37,
Immobilizer
Antenna.>
Replace antenna. Go to step 3.
<Ref. to SL-37,
Immobilizer
Antenna.>
Replace antenna. Go to step 4.
<Ref. to SL-37,
Immobilizer
Antenna.>
Go to step 5. Replace antenna.
<Ref. to SL-37,
Immobilizer
Antenna.>
Go to step 6. Replace antenna.
<Ref. to SL-37,
Immobilizer
Antenna.>
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).
No