B2575

DTC B2575

Diagnostic Instructions

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

DTC Descriptor
DTC B2575 00
- Headlamp Low Beam Control Circuit

Diagnostic Fault Information






Circuit/System Description

When the turn signal/multifunction switch is placed in the headlamp position, ground is applied to the body control module (BCM) through the headlamp low beam signal circuit. The BCM then applies ground to the headlamp low beam relay control circuit which energizes the low beam relay, applying battery voltage through the LOW BEAM fuses to the low beam headlamps. For more detailed information concerning headlamp operation refer to Exterior Lighting Systems Description and Operation.

Conditions for Running the DTC

Battery voltage must be between 9-16 volts.

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.

Actions 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.
* You issue a scan tool CLEAR DTCs command.
* A history DTC will clear once 100 consecutive malfunction-free ignition cycles have occurred.

Circuit/System Testing

1. Ignition OFF, disconnect the low beam relay.
2. Connect a test lamp between the low beam relay control circuit terminal R23 and the voltage supply circuit terminal R22.
3. Command the low beam headlamps 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 open/high resistance. If the circuit tests normal, replace the BCM.

4. If all circuits test normal, test or replace the low beam relay.

Repair Instructions

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

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