Check Key Switch Circuit: Wiring Diagram

Immobilizer system. See appropriate SYSTEM WIRING DIAGRAM article.

Fig 1: Immobilizer System - Wiring Diagram (Key Switch)

Courtesy of SUBARU OF AMERICA, INC.

Step	Check	Yes	No
1 CHECK POWER SUPPLY CIRCUIT. Disconnect the connector from key warning switch. Measure the voltage between key warning switch connector terminal and chassis ground. Connector & terminal (B350) No. 3 (+) - Chassis ground (-):	Is the voltage 10 V or more?	Go to step 2 .	Check the harness for an open or short between the key warning switch and fuse.
2 CHECK KEY WARNING SWITCH. Insert the ignition key in the ignition switch. (OFF or ACC) Measure the resistance between key warning switch connector terminals. Connector & terminal No. 3 - No. 4:	Is the resistance less than 1 Ω?	Go to step 3 .	Replace the key warning switch.
3 CHECK KEY WARNING SWITCH. Remove the ignition key from ignition switch. Measure the resistance between key warning switch connector terminals. Connector & terminal No. 3 - No. 4:	Is the resistance 1 MΩ or more?	Go to step 4 .	Replace the key warning switch.
4 CHECK HARNESS BETWEEN KEY WARNING SWITCH AND BODY INTEGRATED UNIT. Disconnect the connector from body integrated unit. Measure the resistance between key warning switch connector terminal and body integrated unit connector terminal. Connector & terminal (B350) No. 4 - (B280) No. 4:	Is the resistance less than 10 Ω?	Replace the body integrated unit. Refer to BODY INTEGRATED UNIT . Register all ignition keys (transponders). Refer to the "REGISTRATION MANUAL FOR IMMOBILIZER".	Repair the harness between key warning switch and body integrated unit.