B2580

DTC B2580

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 Descriptors

DTC B2580 01
- Headlamp High Beam Control Circuit Short to Voltage

DTC B2580 06
- Headlamp High Beam Control Circuit Open or Short to Ground

Diagnostic Fault Information





Circuit/System Description

With the headlamp switch in the HEAD position, the headlamp switch headlamp ON signal circuit is grounded through the turn signal/multifunction switch at G300. In response to this input, the body control module (BCM) provides ground to either the headlamp low beam relay control circuit or the headlamp high beam relay control circuit. The position of the headlamp dimmer switch determines which relay coil has ground. The BCM supplies ground to the relay coil circuits, if the headlamps are necessary. The underhood fuse block supplies battery positive voltage to both relay switch circuits. When the low beam relay coil is energized, current flows through the LT LOW beam and the RT LOW beam fuses to the low beam headlamps. When the headlamp high beam relay coil is energized, current flows through the LT HI beam and the RT HI beam fuses to the high beam headlamps. Ground for the left headlamp assembly is provided at G101. Ground for the right headlamp assembly is provided at G102. For more detailed information concerning headlamp operation refer to Exterior Lighting Systems Description and Operation.

Conditions for Running the DTC

Battery voltage must be between 9-16 volts.

Conditions for Setting the DTC

* DTC B2580 01 will set when the BCM detects a short to voltage in the headlamp high beam relay control circuit.
* DTC B2580 06 will set when the BCM detects an open or short to ground in the headlamp high beam relay control circuit.

Actions Taken When the DTC Sets

* When DTC B2580 01 is present, the high beam headlamps will not operate.
* When DTC B2580 06 is present, the high beam headlamps will remain ON.

Conditions for Clearing the DTC

* The condition responsible for setting the DTC no longer exists.
* You issue a scan tool CLEAR DTCs command.
* A history DTC will clear once 100 consecutive malfunction-free ignition cycles have occurred.

Circuit/System Testing

1. Ignition OFF, disconnect the high beam relay.
2. Connect a test lamp between the high beam relay control circuit and the voltage supply circuit at the high beam relay terminals.
3. Command the high beam 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 open/high resistance. If the circuit tests normal, replace the BCM.

4. If all circuits test normal, test or replace the high beam relay.

Repair Instructions

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

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