GM Service Manual Online
For 1990-2009 cars only

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 B2580 00: Headlamp High Beam Control Circuit

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

Flash to Pass Switch Signal

1

1

1

--

Headlamp Switch High Beam Signal

1

1

1

--

Headlamp Switch Headlamps ON Signal

B257A 00

1

1

--

Headlamp Switch Headlamps OFF Signal

B257A 00

1

1

--

Park Lamp Switch ON Signal

2

B257A 00

2

--

Headlamp High Beam Relay Control

1

1

B2580 00

--

Headlamp Low Beam Relay Control

1

1

B2575 00

--

LF High Beam Headlamp Control

1

1

1

--

LF Low Beam Headlamp Control

1

1

1

--

RF High Beam Headlamp Control

1

1

1

--

RF Low Beam Headlamp Control

1

1

1

--

LF Headlamp Ground

--

1

--

--

RF Headlamp Ground

--

1

--

--

Headlamp and Panel Dimmer Switch Ground

--

1

--

--

Turn Signal/Multifunction Switch Ground

--

1

--

--

1. Headlamps Malfunction

2. Park, License, and/or Tail Lamps Malfunction

Circuit/System Description

When the turn signal/multifunction switch is placed in the headlamps high or flash to pass (FTP) position, ground is applied to the body control module (BCM) through the headlamp high beam signal circuit or the flash to pass switch signal circuit. The BCM applies ground to the headlamp high beam relay control circuit which energizes the high beam relay. With the high beam relay energized, the switch contacts close allowing battery voltage to flow through the HI BEAM fuses to the high beam headlamps. Ground for the high beam headlamps is supplied at ground G104.

Conditions for Running the DTC

    • Battery voltage must be between 9-16 volts.
    • High beam headlamps ON.

Conditions for Setting the DTC

DTC B2580 00 will set when the BCM detects a short to voltage in the headlamp high beam relay control circuit.

Actions Taken When the DTC Sets

When DTC B2580 00 is present, the high beam headlamps and flash to pass (FTP) 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

Exterior Lights Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Exterior Lighting Systems Description and Operation

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Testing

  1. Ignition OFF, disconnect the high beam relay.
  2. Connect a test lamp between the control circuit terminal 85 and the B+ circuit terminal 86.
  3. Command the High Beams ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.
  4. 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.
  5. If all circuits test normal, test or replace the high beam relay.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Underhood Electrical Center or Junction Block Replacement
    •  Control Module References for BCM replacement, setup, and programming