DTC B278D: Id Code Box Judgment Circuit

DTC detecting condition: 

• When ID code box setting is set to OFF, ID code box ON input is detected.
• When ID code box setting is set to OFF, ID code box LIN signal is received.

Trouble symptom: 

Engine will not start.

Wiring diagram: 

Push button start system Ref. to WIRING SYSTEM>Push Button Start System>WIRING DIAGRAM

Courtesy of SUBARU OF AMERICA, INC.

1. CHECK DTC  .
   1. Turn the ignition switch to OFF.
   2. Using the Subaru Select Monitor, clear the keyless access system memory. Ref. to KEYLESS ACCESS WITH PUSH BUTTON START SYSTEM (DIAGNOSTICS)>Clear Memory Mode 
   3. Turn the ignition switch to OFF → ON.
   4. Read the DTC using Subaru Select Monitor. Ref. to KEYLESS ACCESS WITH PUSH BUTTON START SYSTEM (DIAGNOSTICS)>Read Diagnostic Trouble Code (DTC) 

   Is DTC B278D displayed?

   Yes: Go to  2

   No: Even if DTC is displayed, the circuit has returned to a normal condition at this time. Reproduce the failure, and then perform the diagnosis again.

   NOTE: In this case, temporary poor contact of connector, temporary open or short circuit of harness may be the cause.
2. CHECK HARNESS (GROUND SHORT CIRCUIT)  .
   1. Disconnect the keyless access CONTROL MODULE connector.
   2. Measure the resistance between keyless access CONTROL MODULE connector and chassis ground.

      Connector & terminal 

      (B573) No. 15 - Chassis ground:

   Is the resistance 10 kΩ or more?

   Yes: Replace the keyless access CONTROL MODULE. Ref. to SECURITY AND LOCKS>Keyless Access CONTROL MODULE

   No: Repair or replace the short circuit of the harness.