B1457

DTC B1457

Diagnostic Instructions

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

DTC Descriptors
DTC B1457 02
- AHLD Left Servo Driver Terminal 3 Circuit Short to Ground

DTC B1457 05
- AHLD Left Servo Driver Terminal 3 Circuit Short to Battery or Open

Diagnostic Fault Information





Circuit Description

The headlamp leveling module receives inputs from the front and rear suspension position sensors to determine vehicle pitch. The suspension position sensors send an output to the headlamp leveling module as the vehicle suspension compresses and rebounds. The headlamp leveling module calculates the difference in vehicle pitch and sends a command to the headlamp leveling actuators. The headlamp leveling actuators drive the headlamps to the position commanded by the headlamp leveling module. The headlamp leveling module monitors the headlamp leveling 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.

Conditions for Running the DTC

The headlamp leveling module performs this diagnostic test mode every 0.8 millisecond when the following conditions are met:

* The ignition is in the ON or CRANK position.
* The headlamps are ON.

Conditions for Setting the DTC

B1457 02

This DTC will set when the headlamp leveling module detects a short to ground in the left headlamp leveling actuator motor 3 control circuit after 4 consecutive monitoring cycles.

B1457 05

This DTC will set when the headlamp leveling module detects an open or short to voltage in the left headlamp leveling actuator motor 3 control circuit after 4 consecutive monitoring cycles.

Action Taken When the DTC Sets

When DTC B1457 sets, the headlamp leveling module will disable all requests to both headlamp leveling actuators.

Conditions for Clearing the DTC

* The condition responsible for setting the DTC no longer exists.
* A history DTC will clear once 40 consecutive malfunction free ignition cycles have occurred.

Reference Information
Schematic Reference

Headlight Leveling Schematics (Headlight Leveling Schematics)
Connector End View Reference

Component Connector End Views (Connector Views)
Description and Operation

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

* Circuit Testing (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)
* Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)

Scan Tool Reference

Control Module References (Programming and Relearning) for scan tool information

Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the left headlamp leveling actuator.
2. Ignition ON, verify that a test lamp illuminates between the low reference circuit terminal 2 and B+.

• If the test lamp does not illuminate, test the low reference circuit for a short to voltage or and open/high resistance. If the circuit tests normal, replace the headlamp leveling module.

3. Ignition OFF, connect a test lamp between the control circuit terminal 4 and the low reference circuit terminal 2.
4. Ignition ON, headlamps ON, perform the Headlamp Motor Test with a scan tool. The test lamp should turn ON then OFF as the motor test is performed.

• If the test lamp is always ON, test the control circuit terminal 4 for a short to voltage. If the circuit tests normal, replace the headlamp leveling module.
• If the test lamp is always OFF, test the control circuit terminal 4 for a short to ground or an open/high resistance. If the circuit tests normal, replace the headlamp leveling module.

5. If all circuits test normal, replace the left headlamp leveling actuator.

Repair Instructions

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

* Headlamp Replacement (Service and Repair)
* Control Module References (Programming and Relearning) for headlamp leveling module replacement, setup, and programming