B2580

DTC B2580

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (Diagnostic System Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Strategy Based Diagnosis) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Diagnostic Procedure Instructions) provides an overview of each diagnostic category.

DTC Descriptor
DTC B2580 02
- High Beam Control Circuit Short to Ground

Diagnostic Fault Information





Circuit/System Description

The headlamp high beam relay is supplied with battery voltage at all times. The turn signal/multifunction switch signal circuit is grounded by pressing the turn signal/multifunction switch. The body control module (BCM) energizes the headlamp high beam relay by applying ground to the headlamp high beam relay control circuit. When the headlamp high beam relay is energized, the relay switch contacts close and battery voltage is applied through the high beam lamp fuses to the high beam lamp supply voltage circuit which illuminates the high beam lamps.

Conditions for Running the DTC

High beam lamps ON.

Conditions for Setting the DTC

The BCM detects a short to ground in the headlamp high beam relay control circuit.

Action Taken When the DTC Sets

The high beam headlamps will always be illuminated.

Conditions for Clearing the DTC

* The DTC will be current for as long as the fault is present.
* When the fault is no longer present, the DTC will be a history DTC.
* A history DTC will clear after 50 ignition cycles.

Reference Information
Schematic Reference

Headlights/Daytime Running Lights (DRL) Schematics (Headlights/Daytime Running Lights (DRL) Schematics)
Connector End View Reference

Component Connector End Views (Connector End Views By Name)
Description and Operation

Exterior Lighting Systems Description and Operation (Exterior Lighting Systems)
Electrical Information Reference

* Circuit Testing (Circuit Testing)
* Connector Repairs (Connector Repairs)
* Testing for Intermittent Conditions and Poor Connections (Testing for Intermittent Conditions and Poor Connections)
* Wiring Repairs (Wiring Repairs)

Scan Tool Reference

Control Module References (Programming and Relearning) for scan tool information

Circuit/System Verification

Ignition ON, command the High Beams ON and OFF with a scan tool. The high beam headlamps should turn ON and OFF when changing between the commanded states.

Circuit/System Testing

1. Ignition OFF, disconnect the X5 harness connector at the K9 BCM.
2. Ignition ON, test for greater than 10V between the control circuit terminal 18 and ground.

• If less than the specified range, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the X50A underhood fuse block.

3. If all circuits test normal, replace the K9 BCM.

Repair Instructions

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

* Fuse Block Replacement (Fuse Block Replacement)
* Control Module References (Programming and Relearning) for BCM, replacement, programming and setup