B257D

DTC B257C or B257D

Diagnostic Instructions

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

DTC Descriptors
DTC B257C 00
- Left Headlamp Assembly Malfunction

DTC B257D 00
- Right Headlamp Assembly Malfunction

Circuit/System Description

The headlamp control module calculates the headlamp angle and sends commands to the left and right adaptive forward lighting system headlamp actuators. The headlamp actuators drive the headlamps to the position commanded by the headlamp control module. The headlamp control module monitors the headlamp actuator motor control circuits for proper circuit continuity and for shorts to ground or voltage. If a malfunction is detected, a DTC will be stored in memory and the driver will be notified with a "Service AFL Lamp" message displayed over the driver information center located on the instrument cluster.

Conditions for Running the DTC

* Engine ON.
* Headlamps ON.

Conditions for Setting the DTC

DTC B257C 00

The headlamp control module receives a serial data message from the left headlamp internal logic module that an internal headlamp malfunction has occurred.

DTC B257D 00

The headlamp control module receives a serial data message from the right headlamp internal logic module that an internal headlamp malfunction has occurred.

Actions Taken When the DTC Sets

* Service AFL Lamp message is commanded ON.
* The appropriate headlamp horizontal and vertical controls are disabled.

Conditions for Clearing the DTC

* The condition responsible for setting the DTC no longer exists.
* A history DTC will clear once 50 malfunction-free ignition cycles have occurred.

Diagnostic Aids

DTC B257C and B257D will set when there is an internal malfunction within the left or right headlamp assemblies. No parts are serviceable within the headlamp assemblies so complete headlamp assembly replacement is necessary.

Reference Information
Schematic Reference

Headlights/Daytime Running Lights (DRL) Schematics Headlights/Daytime Running Lights (DRL) Schematics
Connector End View Reference

Component Connector End Views Connector End Views By Name
Description and Operation

Exterior Lighting Systems Description and Operation Exterior Lighting Systems
Electrical Information Reference

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

Scan Tool Reference

Control Module References Control Module References for scan tool information

Circuit/System Testing

1. Ignition ON, with a scan tool, clear the DTC and operate the vehicle within the Conditions for Running the DTC. Verify the DTC does not reset.

• If the DTC resets as current, replace the appropriate headlamp assembly.

Repair Instructions

Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.

* Headlamp Replacement Headlamp Replacement
* Control Module References Control Module References for headlamp control module replacement, setup, and programming