B2575

DTC B2575

DTC DESCRIPTOR

DTC 2575 00: Headlamp Control Circuit




DIAGNOSTIC FAULT INFORMATION

IMPORTANT: Always perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Testing and Inspection

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 engages the headlamp relay and applies voltage through the headlamp fuses to the low beam headlamps.

HEADLAMP SWITCH OPERATION
When the headlamp switch is placed in the ON position, ground is applied to the BCM through the headlamp switch circuit. The BCM then applies a ground to the headlamp low beam relay control circuit. This engages the headlamp relay and applies voltage through the headlamp fuses to the low beam headlamps.

CONDITIONS FOR RUNNING THE DTC
The ignition is ON. The headlamps must be commanded ON by either the BCM or by the headlamp switch.

CONDITIONS FOR SETTING THE DTC
The BCM detects a short to voltage on the low beam headlamps relay control circuit while trying to apply a ground to the circuit.

ACTION TAKEN WHEN THE DTC SETS
The low beam headlamps are not illuminated.

CONDITIONS FOR CLEARING THE DTC
The BCM clears this code from current when the fault is removed from the system.

CIRCUIT/SYSTEM VERIFICATION
Ignition ON, turn the headlamps ON. The headlamps should illuminate.

CIRCUIT/SYSTEM TESTING
1. Clear the DTC, ignition OFF, headlamp switch OFF, disconnect the low beam headlamp relay.
2. Verify a test lamp illuminates between the negative battery terminal and the low beam headlamp relay control circuit.
- If the test lamp does not illuminate, replace the low beam headlamp relay.
3. Test for a short to voltage in the low beam headlamp relay control circuit.
- If all circuits/connections test normal, replace the BCM.

REPAIR INSTRUCTIONS

IMPORTANT: Always perform the Diagnostic Repair Verification after completing the diagnostic procedure.
- Relay Replacement (Within an Electrical Center) Relay Replacement (Attached to Wire Harness)
- Control Module References for BCM replacement, setup, and programming