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 Descriptor

DTC B2580 00
- Headlamp High Beam Control Circuit

Diagnostic Fault Information






Circuit/System Description

Voltage is applied at all times to the high beam headlamp relay from battery voltage. When the multifunction switch is placed in either the FTP or HIGH position, ground is applied to the body control module (BCM). The BCM then applies a ground to the headlamp high beam relay control circuit. This engages the relay and applies voltage through the HI HEADLAMP fuses to both left and right high beam headlamps.

Conditions for Running the DTC

* The headlamps are commanded ON.
* Headlamp dimmer switch must be in the high beam position.

Conditions for Setting the DTC

The BCM detects a short to voltage on the headlamp high beam relay control circuit.

Action Taken When the DTC Sets

The high beam headlamps are inoperative.

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.
* The BCM receives the clear code command from the scan tool.

Circuit/System Verification

Ignition ON, activate the High Beam output control on the scan tool. The High Beam Relay Command parameter in the data list should display On and the high beam headlamps should illuminate.

Circuit/System Testing

1. Ignition OFF, disconnect the harness connector X4 at the BCM.
2. Low beam headlamps ON, verify the high beam headlamps are not on.

^ If the high beam headlamps are on, test the high beam relay control circuit for a short to ground. If the circuit tests normal replace the underhood fuse block.

3. Install a 10A fused jumper wire between the relay control circuit terminal 16 and ground. Verify the high beam headlamps are on.

^ If the high beam headlamps are not on, test the high beam relay control circuit for a short to voltage or an open/high resistance. If the circuit tests normal replace the underhood fuse block.

4. If all circuits test normal, replace the BCM.

Repair Instructions

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

* Underhood Electrical Center or Junction Block Replacement