DTC B2304: Rear Radar On-Off Switch Stuck

DTC detecting condition: 

• BSD/RCTA OFF switch is stuck to ON. (Switch malfunction)
• Switch was left pressed for a prolonged time.
• Defective radar sensor

Trouble symptom: 

• All functions of BSD/RCTA stop.
• Fail icon is displayed in the combination meter LCD display.
• Failure-related notification is displayed for approx. two seconds on LCD display in the combination meter.

Wiring diagram: 

BSD/RCTA system Ref. to WIRING SYSTEM (IMPREZA MODEL)>BLIND SPOT DETECTION/REAR CROSS TRAFFIC ALERT>WIRING DIAGRAM . Ref. to WIRING SYSTEM (CROSSTREK MODEL (EXCEPT FOR HEV))>BLIND SPOT DETECTION/REAR CROSS TRAFFIC ALERT>WIRING DIAGRAM . Ref. to WIRING SYSTEM (CROSSTREK MODEL (HEV))>BLIND SPOT DETECTION/REAR CROSS TRAFFIC ALERT>WIRING DIAGRAM .

Courtesy of SUBARU OF AMERICA, INC.

1. CHECK METER DISPLAY  .
   1. Turn the ignition switch to ON.
   2. Check the display of OFF indicator in the combination meter LCD display.

   Does the display change according to operation of BSD/RCTA OFF switch?

   Yes:  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:

   • Temporary poor contact of connector, temporary open or short circuit of harness may be the cause.
   • User may have kept pressing the switch for 30 seconds or more.

   No:  Go to  2.

2. CHECK DATA MONITOR  .

   Using the Subaru Select Monitor, check the following items in the [Data Monitor] of [Blind Spot Detection/Rear Cross Traffic Alert(LH)]. Ref. to BLIND SPOT DETECTION/REAR CROSS TRAFFIC ALERT (DIAGNOSTICS)>DATA MONITOR .

   • SRVD System ON-OFF flag

   Does the display change according to operation of BSD/RCTA OFF switch?

   Yes:  Check the combination meter. Ref. to COMBINATION METER (DIAGNOSTICS)>BASIC DIAGNOSTIC PROCEDURE .

   No:  Go to  3.

3. INSPECTION OF SWITCH UNIT  .

   Perform unit inspection of the BSD/RCTA OFF switch. Ref. to BLIND SPOT DETECTION/REAR CROSS TRAFFIC ALERT>SWITCHES AND HARNESS .

   Is the check result OK?

   Yes:  Go to  4.

   No:  Replace the BSD/RCTA OFF switch Ref. to BLIND SPOT DETECTION/REAR CROSS TRAFFIC ALERT>SWITCHES AND HARNESS .

4. CHECK BATTERY  .

   Check the battery Ref. to STARTING/CHARGING SYSTEMS (H4DO (EXCEPT FOR HEV))>BATTERY Ref. to STARTING/CHARGING SYSTEMS (H4DO(HEV))>BATTERY .

   Is the check result OK?

   Yes:  Go to  5.

   No:  Charge or replace the battery.

5. CHECK FUSE  .
   1. Turn the ignition switch to OFF.
   2. Check the fuse of BSD/RCTA OFF switch. Ref. to BLIND SPOT DETECTION/REAR CROSS TRAFFIC ALERT>RELAY AND FUSE .

   Is the check result OK?

   Yes:  Go to  6.

   No:  Replace the fuse. If the replaced fuse blows out easily, repair the ground short circuit in harness between the fuse - the SRVD OFF switch.

6. CHECK HARNESS (OPEN CIRCUIT)  .
   1. Disconnect the BSD/RCTA OFF switch connector.
   2. Turn the ignition switch to ON.
   3. Using a tester, measure the voltage between BSD/RCTA OFF switch connector and chassis ground.

      Connector and terminal 

      (i94) No. 6 (+) - Chassis ground (-):

   Is the voltage 10 V or more?

   Yes:  Go to  7.

   No:  Repair the open circuit of harness between the fuse - the BSD/RCTA OFF switch.

7. CHECK HARNESS (OPEN CIRCUIT)  .
   1. Turn the ignition switch to OFF.
   2. Disconnect the radar sensor LH connector.
   3. Using a tester, measure the resistance between BSD/RCTA OFF switch connector and radar sensor LH connector (harness side).

      Connector and terminal 

      (i94) No. 8 - (R25) No. 8:

   Is the resistance less than 1 Ω?

   Yes:  Go to  8.

   No:  Repair the open circuit of harness between BSD/RCTA OFF switch - radar sensor LH.

8. CHECK HARNESS (GROUND SHORT CIRCUIT)  .

   Using a tester, measure the resistance between the BSD/RCTA OFF switch connector (harness side) and the chassis ground.

   Connector and terminal 

   (i94) No. 8 - Chassis ground:

   Is the resistance 1 MΩ or more?

   Yes:  Go to  9.

   No:  Repair the short circuit to ground in harness between BSD/RCTA OFF switch - radar sensor LH.

9. CHECK HARNESS (SHORT CIRCUIT TO POWER SUPPLY)  .
   1. Turn the ignition switch to ON.
   2. Using a tester, measure the voltage between the BSD/RCTA OFF switch connector (harness side) and the chassis ground.

      Connector and terminal 

      (i94) No. 8 (+) - Chassis ground (-):

   Is the voltage less than 1 V?

   Yes:  Go to  10.

   No:  Repair the short circuit to power supply in harness between BSD/RCTA OFF switch - radar sensor LH.

10. CHECK CONNECTOR  .

    Check the radar sensor LH connector. (Insecure connection, poor contact, etc.)

    Is the check result OK?

    Yes:  Go to  11.

    No:  Repair the connector.

11. CHECK BSD/RCTA  .
    1. Restore the vehicle to its original state.
    2. Perform the inspection mode. Ref. to BLIND SPOT DETECTION/REAR CROSS TRAFFIC ALERT (DIAGNOSTICS)>INSPECTION MODE .

    Is DTC B2304 displayed? (Current malfunction)

    Yes:  Replace the radar sensor LH. Ref. to BLIND SPOT DETECTION/REAR CROSS TRAFFIC ALERT>RADAR SENSOR .

    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.