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: Headlamp High Beam Control CircuitDiagnostic Fault Information
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
|---|---|---|---|---|
Low Beam Headlamp Control | 1 | 1 | 1 | -- |
High Beam Headlamp Control | 1 | 1 | 1 | -- |
Headlamp Low Beam Relay Control | 1 | 1 | 1 | -- |
Headlamp High Beam Relay Control | B2580 | B2580 | B2580 | -- |
Headlamp Switch Headlamps Off Signal | 1 | 1 | 1 | -- |
Headlamp Switch Headlamps On Signal | 1 | 1 | 1 | -- |
Flash to Pass Switch Signal | 1 | 1 | 1 | -- |
Headlamp Dimmer Switch High Beam Signal | 1 | 1 | 1 | -- |
Low Beam Headlamp Ground | -- | 1 | -- | -- |
High Beam Headlamp Ground | -- | 1 | -- | -- |
Headlamp Switch Ground | -- | 1 | -- | -- |
Turn Signal/Multifunction Switch Ground | -- | 1 | -- | -- |
1. Headlamps 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 relay control 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 left headlamp is supplied at G101 and the right headlamp receives ground at G100.
Conditions for Running the DTC
| • | Battery voltage must be between 9-16 volts. |
| • | Headlamps ON. |
Conditions for Setting the DTC
DTC B2580 will set when the BCM detects a short to voltage, shorty to ground or an open/high resistance in the headlamp high beam relay control circuit.
Actions Taken When the DTC Sets
When DTC B2580 is set as current, the high beam headlamps and flash to pass (FTP) will be disabled.
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
Headlights/Daytime Running Lights (DRL) Schematics
Connector End View Reference
Description and Operation
Exterior Lighting Systems Description and Operation
Electrical Information Reference
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Testing
- Ignition OFF, disconnect the high beam relay.
- Connect a test lamp between the control circuit terminal 86 and the B+ circuit terminal 85.
- 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 |
