DTC B1574 Key Communication Failure: Wiring Diagram

Immobilizer system. See appropriate SYSTEM WIRING DIAGRAM article.

Fig 1: Immobilizer System - Wiring Diagram (KEY Communication Failure)

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Courtesy of SUBARU OF AMERICA, INC.

DIAGNOSTIC PROCEDURE

Step	Check	Yes	No
1 CHECK BODY INTEGRATED UNIT FUNCTION. Insert the key into the ignition switch (LOCK position), then measure changes in voltage between the antenna connector and the chassis ground. Connector & terminal (B415) No. 1 (+) - Chassis ground (-):	Is the maximum voltage more than 40 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 .	Replace the body integrated unit. Refer to BODY INTEGRATED UNIT . Register all ignition keys (transponders). Refer to the "REGISTRATION MANUAL FOR IMMOBILIZER".
2 CHECK IGNITION KEY (TRANSPONDER). Remove the key from ignition switch. Start the engine using other key which is already registered.	Does the engine start?	Register ignition keys (transponders). Refer to the "REGISTRATION MANUAL FOR IMMOBILIZER".	Replace the body integrated unit. Refer to BODY INTEGRATED UNIT . Register all ignition keys (transponders). Refer to the "REGISTRATION MANUAL FOR IMMOBILIZER".