DTC B2300: Rear Radar Circuit Low

DTC detecting condition: 

• Short circuit to ground in the harness between radar sensor and 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>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.

  NOTE: Check and replace the side that displayed the DTC.

1. CHECK DTC. 

   Read the DTC. Ref. to BLIND SPOT DETECTION/REAR CROSS TRAFFIC ALERT (DIAGNOSTICS)>Read Diagnostic Trouble Code (DTC)>OPERATION .

   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. 

   Read the DTC. Ref. to BLIND SPOT DETECTION/REAR CROSS TRAFFIC ALERT (DIAGNOSTICS)>Read Diagnostic Trouble Code (DTC)>OPERATION .

   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 OPERATION CHECK MODE. 

   Perform the system operation check mode «Door mirror indicator active test» from «Subaru Rear Vehicle Detection(RH)» or «Subaru Rear Vehicle Detection(LH)». Ref. to BLIND SPOT DETECTION/REAR CROSS TRAFFIC ALERT (DIAGNOSTICS)>System Operation Check Mode .

   Does the 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. Disconnect the radar sensor connector.
   2. Disconnect the outer mirror assembly connector.
   3. Using a tester, measure the resistance between radar sensor connector (harness side) and the chassis ground.

      Connector & 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/WINDOWS/MIRRORS>OUTER MIRROR ASSEMBLY .

   Is the check result OK?

   Yes

   Go to  7 .

   No

   Replace the outer mirror assembly. Ref. to GLASS/WINDOWS/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.