DTC B28B6: Pre-Collision Off Switch

Detected when pre-collision brake OFF switch circuit is not installed, open-circuited or is stuck to ON.

DTC detecting condition: 

• Wiring of pre-collision brake OFF switch is not connected.
• Pre-collision brake OFF switch circuit is open.
• Pre-collision brake OFF switch circuit stays ON for 45 seconds or more.

Trouble symptom: 

All functions of EyeSight system do not operate.

Wiring diagram: 

EyeSight system Ref. to WIRING SYSTEM (IMPREZA MODEL)>EYESIGHT SYSTEM>WIRING DIAGRAM . Ref. to WIRING SYSTEM (CROSSTREK MODEL (EXCEPT FOR HEV))>EYESIGHT SYSTEM>WIRING DIAGRAM .

Courtesy of SUBARU OF AMERICA, INC.

1. CHECK DATA MONITOR  .
   1. Turn the ignition switch to ON.
   2. Using the Subaru Select Monitor, check the following items in the [Data Monitor] of [EyeSight]. Ref. to EYESIGHT (DIAGNOSTICS) (EXCEPT FOR HEV)>DATA MONITOR .
      • Pre-Collision Brake OFF SW

   Does the display change according to [ON]/[OFF] operation of [Pre-Collision Brake OFF SW]?

   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  2.

2. CHECK HARNESS  .
   1. Turn the ignition switch to OFF.
   2. Disconnect the stereo camera connector and the pre-collision brake OFF switch connector.
   3. Using the tester, measure the resistance between the stereo camera connector and pre-collision brake OFF switch connector as well as chassis ground.

      Connector and terminal 

      (R406) No. 3 - (R137) No. 12:

      (R406) No. 5 - Chassis ground:

   Is the resistance less than 1 Ω?

   Yes:  Go to  3.

   No:  Repair or replace an open circuit in harness between the stereo camera connector and pre-collision brake OFF switch connector.

3. CHECK HARNESS  .

   Using the tester, measure the resistance between the pre-collision brake OFF switch connector and chassis ground.

   Connector and terminal 

   (R406) No. 3 - Chassis ground:

   Is the resistance 1 MΩ or more?

   Yes:  Go to  4.

   No:  Repair or replace the short circuit to ground in harness between the stereo camera connector and pre-collision brake OFF switch connector.

4. CHECK SWITCH  .

   Check the pre-collision brake OFF switch. Ref. to EYESIGHT>SWITCHES AND HARNESS .

   Is the check result of pre-collision brake OFF switch OK?

   Yes:  Replace the stereo camera. Ref. to EYESIGHT>STEREO CAMERA .

   No:  Replace the pre-collision brake OFF and lane departure warning OFF switch.