Check Key Switch Circuit

CAUTION: When the body integrated unit is replaced, registration of the immobilizer system is required. For details, refer to the "REGISTRATION MANUAL FOR IMMOBILIZER" provided as a separate volume. Contact an Authorized Subaru Dealership.

Wiring diagram:

Immobilizer system Ref. to WIRING SYSTEM>Immobilizer System>WIRING DIAGRAM

Courtesy of SUBARU OF AMERICA, INC.

CHECK POWER SUPPLY CIRCUIT .
1. Disconnect the connector from key warning switch.
2. Measure the voltage between key warning switch connector terminal and chassis ground.
  Connector & terminal
  
  (B555) No. 1 (+) - Chassis ground (-):
Is the voltage 10 V or more?

Yes: Go to 2

No: Check the harness for an open or short between the key warning switch and fuse.
CHECK KEY WARNING SWITCH .
1. Insert the ignition key in the ignition switch. (OFF or ACC)
2. Measure the resistance between key warning switch connector terminals.
  Terminals
  
  No. 1 - No. 2:
Is the resistance less than 1 Ω?

Yes: Go to 3

No: Replace the key warning switch. Ref. to SECURITY AND LOCKS>Key Lock Cylinders
CHECK KEY WARNING SWITCH .
1. Remove the ignition key from ignition switch.
2. Measure the resistance between key warning switch connector terminals.
  Terminals
  
  No. 1 - No. 2:
Is the resistance 1 M? or more?

Yes: Go to 4

No: Replace the key warning switch. Ref. to SECURITY AND LOCKS>Key Lock Cylinders
CHECK HARNESS BETWEEN KEY WARNING SWITCH AND BODY INTEGRATED UNIT (OPEN) .
1. Disconnect the connector from body integrated unit.
2. Measure the resistance between key warning switch connector terminal and body integrated unit connector terminal.
  Connector & terminal
  
  (B555) No. 2 - (B280) No. 4:
Is the resistance less than 10 Ω?

Yes: Replace the body integrated unit. Ref. to SECURITY AND LOCKS>Body Integrated Unit

No: Repair the harness between key warning switch and body integrated unit.