Buick Regal: Lane Departure Warning System Malfunction

Diagnostic Instructions

• Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
• Review Strategy Based Diagnosis for an overview of the diagnostic approach.
• Diagnostic Procedure Instructions provides an overview of each diagnostic category.

Diagnostic Fault Information

1. Lane departure warning switch malfunction.
2. Lane departure warning switch indicator malfunction.

Circuit/System Description

The lane departure warning system is enabled and disabled through the lane departure switch. When enabled, the lane departure warning indicator will illuminate.

For vehicles without UGN, the switch and indicator are connected to the frontview camera module. The frontview camera module supplies a reference voltage to the lane departure switch. When the switch is pressed, the signal circuit is grounded. When enabled, the frontview camera module will illuminate the indicator located in the switch when lane departure warning system is enabled.

With UGN, the indicator and switch are connected to the active safety control module. The active safety control module receives input from several modules including the Parking Assist Control Module to provide additional features. The lane departure warning alerts and DTCs are from the frontview camera module with the exception of the indicator DTCs which are sent by the active safety control module.

There are no switch DTCs for vehicles with the active safety control module.

When the system is operating and can detect the lane markings, the frontview camera module will request via serial data communications that the instrument cluster illuminate the green lane departure warning symbol. If the frontview camera module detects that the vehicle unintentionally crosses a lane marking without the turn signal being used, the module will request the instrument cluster to flash the amber lane departure warning indicator. An audible warning will also sound three times when the amber lane departure warning indicator in the instrument cluster is flashing.

Diagnostic Aids

Certain factors will affect the operation of the lane departure warning system. When the system is operating properly, the indicator will illuminate on the instrument cluster. This indicates that all of the required operating conditions to permit lane departure warning have been met. The indicator will not appear when the system is having difficulty seeing the lines on the road or if the view of the frontview camera is blocked with mud, dirt, snow, ice, or slush, if the windshield is damaged, or when weather limits visibility, such as while driving in fog, rain, or snow conditions. This is normal operation, the vehicle does not need service. Additionally, lane departure warnings may occasionally occur in a properly operating vehicle due to tar marks, shadows, cracks in the road, or other road imperfections.

This is normal system operation and the vehicle does not require service. The driver information center may also display Lane Departure System Unavailable due to the temporary conditions listed above.

Additionally, the Frontview Camera Disable History can give useful hints about what affected the operation of the lane departure warning system. For the Frontview Camera Disable History, refer to Control Module References for scan tool information.

Reference Information

Schematic Reference

Driver Assistance Systems Wiring Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

Lane Departure Warning Description and Operation

Electrical Information Reference

• Circuit Testing
• Connector Repairs
• Testing for Intermittent Conditions and Poor Connections
• Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information.

Circuit/System Verification

1. Ignition ON.

2. Verify that DTC B356A is not set.

• If the DTC is set

Refer to DTC B356A.

• Go to next step: If the DTC is not set

3. Verify that DTC B0987 is not set.

• If the DTC is set

Refer to DTC B0987.

• Go to next step: If the DTC is not set

4. Verify the scan tool Frontview Camera System Status parameter is Normal.

• If the parameter is Undefined or Malfunction

Refer to Diagnostic Aids.

• Go to next step: If the parameter is Normal

5. Verify the scan tool Lane Departure Warning Switch Status parameter changes between Active and Inactive when pressing the lane departure warning switch.

• If the parameter does not change between Active and Inactive

Refer to DTC B356A.

• Go to next step: If the parameter changes between Active and Inactive

6. Verify the scan tool Lane Departure Warning Indicator turns ON and OFF when commanding the Lane Departure Warning Indicator On and Off with a scan tool.

• If the indicator does not turn on and off

Refer to DTC B0987.

• Go to next step: If the indicator turns on and off

7. All OK.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

Control Module References for control module replacement, programming and setup.

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