GM Service Manual Online
For 1990-2009 cars only

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.

DTC Descriptor

DTC B101E 4A: ECU Software Performance Checksum Error

DTC B101E 4B: ECU Software Performance Calibration Not Learned

Circuit/System Description

The lane departure warning system is controlled by the vehicle direction alert alarm warning (VDAAW) module mounted on the windshield. Lane departure warning is enabled and disabled through a switch located in the headlamp switch assembly. When enabled, the VDAAW module will illuminate the indicator located in the switch.

When the system is operating and can detect the lane markings, the VDAAW module will request via serial data communications that the instrument panel cluster (IPC) illuminate the green lane departure ready-to-assist indicator. If the VDAAW module detects that the vehicle has crosses a lane marking without the turn signal being used, the module will request that the IPC flash the yellow lane departure warning indicator. An audible warning will also sound three times when the yellow IPC indicator is flashing.

Conditions for Running the DTC

Ignition ON.

Conditions for Setting the DTC

B101E 4A

A memory checksum mismatch has been detected

B101E 4B

A calibration error has been detected

Action Taken When the DTC Sets

    • Lane departure warning is disabled
    • SERVICE LANE DEPARTURE SYSTEM is displayed on the DIC.

Conditions for Clearing the DTC

    • The condition responsible for setting the DTC no longer exists.
    • A history DTC will clear once 100 consecutive malfunction-free ignition cycles have occurred.

Reference Information

Schematic Reference

Object Detection Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Object Detection 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. Verify DTC B101E 4B is not set.
  2. If the DTC is set, perform the Vehicle Direction Alert Alarm Warning Module Calibration procedure. If the DTC resets, replace the VDAAW module.
  3. Replace the VDAAW module.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for VDAAW module replacement, setup, and programming