LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Subaru >> 2013 >> Legacy Base, Automatic CVT Trans >> Repair and Diagnosis (Single Page) >> Accessories & Equipment >> Anti-Theft Systems >> Security And Locks - Keyless Access (W/Push Button Start) (Diagnostics) >> Diagnostic Procedure with Diagnostic Trouble Code (DTC) >> DTC B278D Id Code Box Recognition Judgment Abnormal >> Diagnostic Procedure
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Diagnostic Procedure

DIAGNOSTIC PROCEDURE

Step Check Yes No
1 CHECK DTC. 
  1. Turn the ignition switch to OFF.
  2. Using the Subaru Select Monitor, clear the keyless access system memory.
  3. Turn the ignition switch to OFF → ON.
  4. Use the Subaru Select Monitor and read DTCs.
 Is B278D displayed? Go to step 2  . System is normal. It is possible that temporary poor contact occurs.
2 CHECK HARNESS. 
  1. Disconnect the keyless access CM connector.
  2. Measure the resistance between keyless access CM connector and chassis ground.

    Connector & terminal 

    (i241) No. 15 - Chassis ground: 

 With ID code box:
Is the resistance 1 Ω or less?
Without ID code box:
Is the resistance 10 kΩ or more? Or is the terminal (i242)
No. 15 disconnected?		 Replace the keyless access CM. < Refer to KEYLESS ACCESS CM . > Repair or replace the short circuit of the harness.
scientia non olet · About LEMON Manuals