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 : Headlamp High Beam Control Circuit Short to VoltageDTC B2580 06 : Headlamp High Beam Control Circuit Open or Short to Ground
Diagnostic Fault Information
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
|---|---|---|---|---|
Flash to Pass Switch Signal | 1 | 1 | 1 | -- |
Headlamp High Beam Relay Control | B2580 06 | B2580 06 | B2580 01 | -- |
Headlamp Switch Signal | 1 | 1 | 1 | -- |
Headlamp Dimmer Switch High Beam Signal | 1 | 1 | 1 | -- |
Headlamp Switch Headlamps On Signal | 1 | 1 | 1 | -- |
Headlamp Switch Headlamps Off Signal | 1 | 1 | 1 | -- |
LF High Beam Headlamp Voltage Supply | 1 | 1 | 1 | -- |
LF Low Beam Headlamp Voltage Supply | 1 | 1 | 1 | -- |
RF High Beam Headlamp Voltage Supply | 1 | 1 | 1 | -- |
RF Low Beam Headlamp Voltage Supply | 1 | 1 | 1 | -- |
LF Headlamp Ground | -- | 1 | -- | -- |
RF Headlamp Ground | -- | 1 | -- | -- |
Turn Signal/Multifunction Switch Ground | -- | 1 | -- | -- |
1. Headlamp Switch Malfunction | ||||
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 through the headlamp switch signal 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 LO BEAM and HI BEAM relays are supplied with battery positive voltage at there coil and switch input circuits. When the low beam relay coil is energized, current flows through the LH LOW and the RH LOW fuses to the low beam headlamps. When the headlamp high beam relay coil is energized, current flows through the LH HIGH and the RH HIGH fuses to the high beam headlamps. The headlights may be switched to high beam with the movement of the headlamp dimmer switch lever. With the headlamp dimmer switch in the high beam position the BCM sends a message via GMLAN to the instrument panel cluster (IPC) requesting the IPC to illuminate the high beam indicator. Ground for the left headlamp assembly is provided at G101. Ground for the right headlamp assembly is provided at G102.
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. |
Reference Information
Schematic Reference
Headlights/Daytime Running Lights (DRL) Schematics
Connector End View Reference
Lighting Systems Connector End Views
Electrical Information Reference
Scan Tool Reference
Circuit/System Testing
- Ignition OFF, disconnect the high beam relay.
- Connect a test lamp between the high beam relay control circuit and the voltage supply circuit at the high beam relay terminals.
- 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 all circuits test normal, test or replace the high beam relay.
| ⇒ | 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. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for BCM replacement, setup and programming |
