Subaru 2004 Forester, Service Manual

Page: 619 / 622

IM-19
IMMOBILIZER (DIAGNOSTIC)
Diagnostics Procedure with Diagnostic Trouble Code (DTC)
C: DTC P1574 KEY COMMUNICATION FAILURE
DIAGNOSIS :
Failure of IMM ECM to verify key (transponder) ID code
Step Check Yes No
1 CHECK IMM ECM FUNCTION.
Insert the key to ignition switch (LOCK posi-
tion), measure changes in voltage between
Antenna connector.
Connector & terminal
(B142) 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 insert-
ing the key)
Go to step 2. 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).
2 CHECK IGNITION KEY (TRANSPONDER).
1) Remove the key from ignition switch.
2) Start the engine using other keys that have
undergone the teaching operation, furnished
with vehicle.
Does the engine start? Replace the igni-
tion key (including
the transponder).
Then perform
teaching opera-
tion. Refer to the
teaching opera-
tion manual (Pub.
No. S0820GZ). 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).