Service Information

Volt

DTC B2580

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 Descriptors

DTC B2580 01: Main Beam Control Circuit Short to Battery

DTC B2580 02: Main Beam Control Circuit Short to Ground

DTC B2580 04: Main Beam Control Circuit Open

Diagnostic Fault Information

Circuit	Short to Ground	Open/High Resistance	Short to Voltage	Signal Performance
Headlamp Main Beam Relay Control	B2580 02, B2580 04	B2580 02, B2580 04	B2580 01	--
Headlamp Main Beam Control - Left	1	1	1	--
Headlamp Main Beam Control - Right	1	1	1	--
Headlamp Ground - Left	--	1	--	--
Headlamp Ground - Right	--	1	--	--
1. Headlamps Malfunction

When the dipped beam headlamps are on and the indicator/multifunction switch is placed in the main beam position, ground is applied to the body control module (BCM) through the main beam signal circuit. The BCM responds to the main beam request by applying ground to the main beam relay control circuit which energises the headlamp main beam relay. With the main beam relay energised, the switch contacts close allowing battery voltage to flow through the main beam fuses to the main beam control circuits illuminating the main beam headlamps.

Conditions for Running the DTC

•	Battery voltage must be between 9-16 V.

•	Main beam headlamps ON.

Conditions for Setting the DTC

DTC B2580 01

The BCM detects a short to voltage in the headlamp main beam relay control circuit.

DTC B2580 02 and B2580 04

The BCM detects a short to ground or an open/high resistance in the headlamp main beam control circuit.

Action Taken When the DTC Sets

•	For an open/high resistance fault, the main beam headlamps and flash to pass function are inoperative. The main beam indicator on the instrument cluster operates normally.

•	For a short to ground fault, the main beam headlamps and main beam indicator on the instrument cluster are always ON with the headlamp switch in the AUTO or headlamps positions.

•	For a short to voltage fault, the main beam headlamps and flash to pass function are inoperative.

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 vehicle ON/OFF switch cycles have occurred.

Reference Information

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

Vehicle OFF, disconnect the X1 harness connector at the X50A Fuse Block - Under-bonnet.
Connect a test lamp between the control circuit terminal 18 and B+.
Vehicle in Service Mode, command the Main Beams 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 K9 Body Control Module.

⇒	If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the K9 Body Control Module.

If all circuits test normal, replace the X50A Fuse Block - Under-bonnet.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

•	Accessory Wiring Junction Block Replacement

•	Control Module References for BCM replacement, programming and setup