DTC B28B7: LDP Off Switch

Detected when lane departure warning OFF switch circuit is not installed, open-circuited, or is stuck to ON.

DTC detecting condition: 

• Wiring of lane departure warning OFF switch is not connected.
• Lane departure warning OFF switch circuit is open.
• Lane departure warning 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 .
      • Lane Departure Warning OFF SW

   Does the display change according to [ON]/[OFF] operation of [Lane Departure Warning 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 lane departure warning OFF switch connector.
   3. Using the tester, measure the resistance between the stereo camera connector and lane departure warning OFF switch connector.

      Connector and terminal 

      (R406) No. 4 - (R137) No. 13:

      (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 lane departure warning OFF switch connector.

3. CHECK HARNESS  .

   Using the tester, measure the resistance between the lane departure warning OFF switch connector and chassis ground.

   Connector and terminal 

   (R406) No. 4 - 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 lane departure warning OFF switch connector.

4. CHECK SWITCH  .

   Check the lane departure warning OFF switch. Ref. to EYESIGHT>SWITCHES AND HARNESS .

   Is the check result of lane departure warning 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.