Check Key Switch Circuit

Trouble symptom: 

Engine does not start.

Trouble causes: 

• Key warning switch circuit malfunction
• Key warning switch malfunction

Wiring diagram: 

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

Courtesy of SUBARU OF AMERICA, INC.

1. 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 

      (i63) 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.

2. CHECK KEY WARNING SWITCH  .
   1. Turn the ignition switch to OFF.
   2. Insert the ignition key in the ignition switch. (OFF or ACC)
   3. 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 .

3. 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 MΩ or more?

   Yes:  Go to  4.

   No:  Replace the key warning switch. Ref. to SECURITY AND LOCKS>KEY LOCK CYLINDERS .

4. CHECK DATA MONITOR  .
   1. Turn the ignition switch to ON.
   2. Using the Subaru Select Monitor, check the following items under the [Data monitor] of [Body Control] or [Immobilizer]. Ref. to BODY CONTROL (DIAGNOSTICS)>DATA MONITOR . Ref. to IMMOBILIZER (DIAGNOSTICS)>DATA MONITOR .
   • Body Control
     • key-lock warning SW
   • Immobilizer
   • key-lock warning SW Input

   Is [ON] displayed?

   Yes:  Replace the body integrated unit (except for C5 model) Ref. to SECURITY AND LOCKS>BODY INTEGRATED UNIT . or the immobilizer Control Module (C5 model) Ref. to SECURITY AND LOCKS>IMMOBILIZER CONTROL MODULE .

   No:  Go to  5.

5. CHECK HARNESS BETWEEN KEY WARNING SWITCH AND BODY INTEGRATED UNIT (EXCEPT FOR C5 MODEL) OR IMMOBILIZER CONTROL MODULE (C5 MODEL)  .
   1. Turn the ignition switch to OFF.
   2. Disconnect the connector from the body integrated unit (except for C5 model) or the immobilizer Control Module (C5 model).
   3. Measure the resistance between key warning switch connector terminal and body integrated unit (except for C5 model) or immobilizer Control Module (C5 model) connector terminal.

      Connector & terminal 

      Body integrated unit (except for C5 model) 

      (i63) No. 2 - (i84) No. 1:

      Immobilizer Control Module (C5 model) 

      (i63) No. 2 - (i34) No. 3:

   Is the resistance less than 10 Ω?

   Yes:  Replace the body integrated unit (except for C5 model) Ref. to SECURITY AND LOCKS>BODY INTEGRATED UNIT . or the immobilizer Control Module (C5 model) Ref. to SECURITY AND LOCKS>IMMOBILIZER CONTROL MODULE .

   No:  Repair harness between key warning switch and body integrated unit (except for C5 model) or immobilizer Control Module (C5 model).