B2575

DTC B2575

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 Descriptor
DTC 2575 00
- Headlamp Control Circuit

Diagnostic Fault Information





Circuit/System Description

Two different inputs to the body control module (BCM) can turn ON the low beam headlamps. The headlamp switch and the ambient light sensor.

Automatic Headlamps Operation

When the ambient light sensor detects a low light condition, the BCM then applies a ground to the headlamp low beam relay control circuit. This energizes the LO BEAM PCB relay and applies voltage through the LO BEAM fuses to the headlamp assemblies.

Headlamp Switch Operation

When the headlamp switch is placed in the ON position, ground is applied to the BCM through the headlamp switch headlamps ON signal circuit. The BCM then applies a ground to the headlamp low beam relay control circuit. This energizes the LO BEAM PCB relay and applies voltage through the headlamp LO BEAM fuses to the headlamps assemblies.

Conditions for Running the DTC

* Battery voltage must be between 9-16 volts.
* Headlamps ON.

Conditions for Setting the DTC

DTC B2575 00 will set when the BCM detects a short to voltage in the headlamp low beam relay control circuit.

Action Taken When the DTC Sets

When DTC B2575 00 is present, the low beam headlamps will not operate.

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

Headlights/Daytime Running Lights (DRL) Schematics (Headlights/Daytime Running Lights (DRL) 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 (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 (Programming and Relearning) for scan tool information

Circuit/System Testing

1. Ignition OFF, disconnect the X2 harness connector at the underhood fuse block.
2. Connect a test lamp between the control circuit terminal 10 and B+.
3. Command the Low Beams ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.

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

4. If the circuit tests normal, test or replace the underhood fuse block.

Repair Instructions

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

* Underhood Electrical Center or Junction Block Replacement (Removal and Replacement)
* Control Module References (Programming and Relearning) for BCM replacement, setup, and programming