LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Subaru >> 2016 >> WRX Base >> Repair and Diagnosis >> Body & Frame >> Door Locks >> Anti-Theft System - Security And Locks >> Keyless Entry System >> Inspection >> Check Key Warning Switch
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Check Key Warning Switch

DIAGNOSTIC PROCEDURE

Step Check Yes No
1 CHECK CURRENT DATA. 
Using the Subaru Select Monitor, display the data of «key-lock warning SW».
NOTE: For detailed operation procedures, refer to "Application help".
Is the normal input signal displayed when the key is inserted in/removed from the ignition switch? The key warning switch is OK. Go to step 2. 
2 CHECK FUSE. 
Remove and visually check fuse No. 14 (in the main fuse box).
Is the fuse blown out? Replace the fuse with a new part. Go to step 3. 
3 CHECK KEY WARNING SWITCH CIRCUIT. 
  1. Disconnect the connector of body integrated unit.
  2. Insert the key into ignition switch. (LOCK position)
  3. Measure the voltage between the body integrated unit connector and chassis ground.

    Connector & terminal 

    (B280) No. 4 (+) - Chassis ground (-): 

Is the voltage 9 V or more? Go to step 4.  Go to step 5. 
4 CHECK KEY WARNING SWITCH CIRCUIT. 
  1. Remove the key from ignition switch.
  2. Measure the voltage between the body integrated unit connector and chassis ground.

    Connector & terminal 

    (B280) No. 4 (+) - Chassis ground (-): 

Is the voltage less than 1.5 V? The key warning switch is OK. Go to step 5. 
5 CHECK KEY WARNING SWITCH. 
  1. Disconnect the connector of key warning switch.
  2. Insert the key into ignition switch. (LOCK position)
  3. Measure the resistance between key warning switch terminals.

    Terminals 

    No. 1 - No. 2: 

Is the resistance less than 1 Ω? Go to step 6.  Replace the key warning switch.
6 CHECK KEY WARNING SWITCH. 
  1. Remove the key from ignition switch.
  2. Measure the resistance between key warning switch terminals.

    Terminals 

    No. 1 - No. 2: 

Is the resistance 1 MΩ or more? Check the following:
  • Harness for open circuits and shorts between the key warning switch and fuse.
  • Harness for open or short between the body integrated unit and key warning switch.
Replace the key warning switch.