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 B2575 00

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Headlamp Control Circuit

Diagnostic Fault Information






Circuit/System Description

The low beam headlamps are controlled by two different inputs to the body control module (BCM), the headlamp switch, or when in the Auto mode, the ambient light sensor. When the BCM receives a low beam headlamps ON command, it grounds the headlamp low beam relay control circuit in order to energize the low beam PCB relay. With the relay energized, battery voltage is applied through switch side of the relay, both LO BEAM fuses, and the low beam supply voltage circuits to the low beam headlamps.

Conditions for Running the DTC

* The low beam headlamps are commanded ON.

* The headlamp dimmer switch must be in the low beam position.

Conditions for Setting the DTC

The BCM detects a short to voltage on the headlamp low beam relay control circuit.

Action Taken When the DTC Sets

The BCM will deactivate the headlamp low beam PCB relay for the remainder of the ignition cycle.

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 1-2 Shift Solenoid (SS) Valve (M30)

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 Verification

Ignition ON, turn the headlamps ON. The headlamps should illuminate.

Circuit/System Testing

1. Ignition OFF, disconnect the X5 harness connector at the BCM.

2. Ignition ON, verify that a test lamp does not illuminate between the control circuit terminal 23 and B+.

• If the test lamp illuminates, test the control circuit for a short to ground. If the circuit tests normal, replace the underhood fuse block.

3. Install a 10 A fused jumper wire between the control circuit terminal 23 and ground. The low beam headlamps should illuminate.

• If the low beam headlamps do not illuminate, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the underhood fuse block.

4. If all circuits test normal, replace the BCM.

Repair Instructions

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

* Underhood Electrical Center or Junction Block Replacement Underhood Electrical Center or Junction Block Replacement

* Control Module References Control Module References for BCM replacement, programming and setup