B2575

DTC B2575

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 B2575 01
- Headlamp Control Circuit Short to Battery

DTC B2575 06
- Headlamp Control Circuit Short to Short to Ground or Open

Diagnostic Fault Information





Circuit/System Description

Battery positive voltage is applied at all times to both the coil and switch sides of the Low Beam relay located in the underhood fuse block. 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. With the low beam relay energized, the switch contacts close allowing battery voltage to flow through the LOW BEAM fuses to the low beam headlamps. Ground for the left headlamp is supplied at G101 and the right headlamp receives ground at G102.

Conditions for Running the DTC

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

Conditions for Setting the DTC

B2575 01

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

B2575 06

The DTC will set when the BCM detects a short to ground or an open in the low beam relay control circuit.

Action Taken When the DTC Sets

* When DTC B2575 01 is present, the low beam headlamps will not operate.
* When DTC B2575 06 is present, the low beam headlamps will be ON at all times or 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) Schematic)
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 low beam relay.
2. Connect a test lamp between the control circuit terminal 86 and the B+ circuit terminal 85.
3. Command the 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 an 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 (Verification Tests) after completing the diagnostic procedure.

* Relay Replacement (Attached to Wire Harness) (Relay Replacement (Attached to Wire Harness))Relay Replacement (Within an Electrical Center) (Relay Replacement (Within an Electrical Center))
* Control Module References (Programming and Relearning) for BCM replacement, setup, and programming