Diagnostic Instructions
| • | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
| • | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
| • | Diagnostic Procedure Instructions provides an overview of each diagnostic category. |
DTC Descriptor
DTC 2575 00: Headlamp Control CircuitDiagnostic Fault Information
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
|---|---|---|---|---|
Headlamp Low Beam Relay Control | 1 | 1 | B2575 00 | -- |
1. Headlamps Malfunction | ||||
Circuit/System Description
Voltage is applied at all times to the low beam headlamp relay from battery voltage. 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 voltage is applied through the switch side of the relay and both low beam headlamp fuses to the low beam headlamps.
Headlamp Switch Operation
When the headlamp switch is placed in the ON position, ground is applied through the headlamp switch headlamps On signal circuit to the BCM. The BCM then applies a ground through the headlamp low beam relay control circuit. This energizes the LO BEAM PCB Relay and voltage is applied through the switch side of the relay and both low beam headlamp fuses to the low beam headlamps.
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
Connector End View Reference
Description and Operation
Exterior Lighting Systems Description and Operation
Electrical Information Reference
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Testing
- Ignition OFF, disconnect the X2 harness connector at the underhood fuse block.
- Connect a test lamp between the control circuit terminal K3 and B+.
- Ignition ON, 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 circuit tests normal, replace the underhood fuse block.
| ⇒ | 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. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for BCM replacement, setup, and programming |
