Diagnostic Procedure for Subaru Select Monitor Communication: Inspection

When communication with the radar sensor is impossible

Detecting condition:

Defective harness connector
Power supply circuit malfunction
Defective radar sensor
Defective CAN communication circuit
Defective Subaru Select Monitor

Trouble symptom:

Communication is impossible between radar sensor and Subaru Select Monitor.

Wiring diagram:

BSD/RCTA system Ref. to WIRING SYSTEM>BLIND SPOT DETECTION/REAR CROSS TRAFFIC ALERT>WIRING DIAGRAM

Courtesy of SUBARU OF AMERICA, INC.

CAUTION:

Before performing diagnosis, refer to "CAUTION" in "General Description". Ref. to BLIND SPOT DETECTION/REAR CROSS TRAFFIC ALERT (DIAGNOSTICS)>GENERAL DESCRIPTION>CAUTION

CHECK FUSE .
1. Turn the ignition switch to OFF.
2. Check the fuse for radar sensor LH. Ref. to WIRING SYSTEM>BLIND SPOT DETECTION/REAR CROSS TRAFFIC ALERT>WIRING DIAGRAM
Is the check result OK?

Yes : Go to 2.

No : Replace the fuse. If the replaced fuse has blown out immediately, repair the short circuit to ground in harness between fuse - radar sensor LH.
CHECK HARNESS (OPEN CIRCUIT) .
1. Disconnect the radar sensor LH connector.
2. Turn the ignition switch to ON.
3. Using a tester, measure the voltage between radar sensor LH connector (harness side) and chassis ground.
  Connector & terminal
  
  (L107) No. 5 (+) - Chassis ground (-):
Is the voltage 10 V or more?

Yes : Go to 3.

No : Repair the open circuit of harness between fuse - radar sensor LH connector.
CHECK HARNESS (OPEN CIRCUIT) .
1. Turn the ignition switch to OFF.
2. Using a tester, measure the resistance between radar sensor LH connector (harness side) and chassis ground.
  Connector & terminal
  
  (L107) No. 10 - Chassis ground:
Is the resistance less than 1 Ω?

Yes : Go to 4.

No : Repair the open circuit in harness between radar sensor and chassis ground.
CHECK LAN SYSTEM .
1. Connect the radar sensor LH connector.
2. Inspect LAN system. Ref. to LAN SYSTEM (DIAGNOSTICS)>BASIC DIAGNOSTIC PROCEDURE>PROCEDURE
Is the check result OK?

Yes : Go to 5.

No : Perform the inspection according to the diagnosis for LAN system.
CHECK RADAR SENSOR .
Communicate with the radar sensor.

Is communication possible?

Yes : 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 :
- Replace the radar sensor LH, when communication with the radar sensor LH is not possible. Ref. to BLIND SPOT DETECTION/REAR CROSS TRAFFIC ALERT>RADAR SENSOR
- Replace the radar sensor RH, when communication with the radar sensor RH is not possible and the radar sensor LH displays DTC B2350. When DTC B2350 is not displayed, replace the radar sensor LH. Ref. to BLIND SPOT DETECTION/REAR CROSS TRAFFIC ALERT>RADAR SENSOR