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 01
- Headlamp Control Circuit Short to Battery

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

Circuit/System Description

The body control module (BCM) turns on the LOW BEAM relay when the ambient light sensor senses a dark condition or the low beam headlamps are requested ON. Battery positive voltage is supplied to the LOW BEAM relay at all times. The BCM grounds the LOW BEAM relay control circuit in order to activate the relay.

Conditions for Running the DTC

* The ignition switch is in the ON position.
* The ambient light sensor senses a dark condition, automatic lamp control (ALC) headlamps ON.

Conditions for Setting the DTC

B2575 01

Will set if there is a short to voltage in the low beam relay control circuit.

B2575 06

Will set if there is an open or short to ground in the low beam relay control circuit.

Action Taken When the DTC Sets

* The SERVICE indicator illuminates.
* The check gages chime sounds.

Conditions for Clearing the DTC

* The conditions for setting the DTC are no longer present.
* A history DTC clears after 100 malfunction-free ignition cycles.

Circuit/System Testing

1. Ignition OFF, disconnect the LO/BEAM relay.
2. Ignition ON, verify that a test lamp illuminates between the B+ circuit of the LO/BEAM relay and ground.

^ If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.

3. Connect a test lamp between the B+ circuit of the LO/BEAM relay and the control circuit of the LO/BEAM relay.
4. Command the backup lamps 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.

5. If all circuits test normal, replace the LO/BEAM relay.

Repair Instructions

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

* Relay Replacement (Attached to Wire Harness)