DTC B2300: Rear Radar Circuit Low

DTC detecting condition: 

• Short circuit to ground in the harness between radar sensor - outer mirror assembly.
• Ground short circuit of the harness in outer mirror assembly module (Malfunction of the outer mirror assembly)
• 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 .

• Radar sensor LH

  Courtesy of SUBARU OF AMERICA, INC.

• Radar sensor RH

  Courtesy of SUBARU OF AMERICA, INC.

1. CHECK DTC  .
   1. Turn the ignition switch to ON.
   2. Using the Subaru Select Monitor, read the DTCs of [Blind Spot Detection/Rear Cross Traffic Alert(RH)] or [Blind Spot Detection/Rear Cross Traffic Alert(LH)]. Ref. to BLIND SPOT DETECTION/REAR CROSS TRAFFIC ALERT (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC) .
      • Blind Spot Detection/Rear Cross Traffic Alert(RH)
      • Blind Spot Detection/Rear Cross Traffic Alert(LH)

   Is DTC B2327 displayed? (Current malfunction)

   Yes:  Perform the diagnosis of DTC B2327. Ref. to BLIND SPOT DETECTION/REAR CROSS TRAFFIC ALERT (DIAGNOSTICS)>DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)>DTC B2327: REAR RADAR INTERNAL FAILURE (INTERNAL ELECTRIC CIRCUIT) .

   No:  Go to  2.

2. CHECK DTC  .

   Using the Subaru Select Monitor, read the DTCs of [Blind Spot Detection/Rear Cross Traffic Alert(RH)] or [Blind Spot Detection/Rear Cross Traffic Alert(LH)]. Ref. to BLIND SPOT DETECTION/REAR CROSS TRAFFIC ALERT (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC) .

   • Blind Spot Detection/Rear Cross Traffic Alert(RH)
   • Blind Spot Detection/Rear Cross Traffic Alert(LH)

   Is DTC B2300 displayed? (Current malfunction)

   Yes:  Go to  3.

   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.
3. CHECK OUTER MIRROR ASSEMBLY INDICATOR  .

   Using the Subaru Select Monitor, execute the following items under the [Active Test] of [Blind Spot Detection/Rear Cross Traffic Alert(RH)] or [Blind Spot Detection/Rear Cross Traffic Alert(LH)]. Ref. to BLIND SPOT DETECTION/REAR CROSS TRAFFIC ALERT (DIAGNOSTICS)>ACTIVE TEST .

   • Door mirror indicator active test

   Does the outer mirror assembly indicator illuminate?

   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: In this case, temporary poor contact of connector, temporary open or short circuit of harness may be the cause.

   No:  Go to  4.

4. CHECK HARNESS (GROUND SHORT CIRCUIT)  .
   1. Turn the ignition switch to OFF.
   2. Disconnect the radar sensor connector.
   3. Disconnect the outer mirror assembly connector.
   4. Using a tester, measure the resistance between radar sensor connector (harness side) and the chassis ground.

      Connector and terminal 

      Radar sensor LH 

      (R25) No. 4 - Chassis ground:

      Radar sensor RH 

      (R61) No. 4 - Chassis ground:

   Is the resistance 1 MΩ or more?

   Yes:  Go to  5.

   No:  Repair the short to ground in harness between radar sensor connector and outer mirror assembly connector.

5. CHECK CONNECTOR  .

   Check the radar sensor connector and the outer mirror assembly connector. (Insecure connection, poor contact, etc.)

   Is the check result OK?

   Yes:  Go to  6.

   No:  Repair the connector.

6. CHECK OUTER MIRROR ASSEMBLY  .

   Perform unit-check for the outer mirror assembly. Ref. to GLASS/WINDOW/MIRRORS>OUTER MIRROR ASSEMBLY .

   Is the check result OK?

   Yes:  Go to  7.

   No:  Replace the outer mirror assembly. Ref. to GLASS/WINDOW/MIRRORS>OUTER MIRROR ASSEMBLY .

7. 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 B2300 displayed? (Current malfunction)

   Yes:  Replace the radar sensor. 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.