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 (CROSSTREK MODEL (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) (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 precollision 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>INSPECTION>PRE-COLLISION BRAKE OFF SWITCH AND LANE DEPARTURE WARNING OFF SWITCH .

   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.