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 B2575 00: Headlamp Low Beam Control CircuitDiagnostic Fault Information
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
|---|---|---|---|---|
Headlamp Switch High Beam Signal | 2 | 2 | 2 | -- |
Headlamp Switch Headlamps ON Signal | 3 | 3 | 3 | -- |
Headlamp Switch Headlamps OFF Signal | 3 | 3 | 3 | -- |
Headlamp High Beam Relay Control | 2 | 2 | 2 | -- |
Headlamp Low Beam Relay Control | 1 | 1 | B2575 00 | -- |
LF High Beam Headlamp Control | 2 | 2 | 2 | -- |
LF Low Beam Headlamp Control | 1 | 1 | 1 | -- |
RF High Beam Headlamp Control | 2 | 2 | 2 | -- |
RF Low Beam Headlamp Control | 1 | 1 | 1 | -- |
LF Headlamp Ground | -- | 1 | -- | -- |
RF Headlamp Ground | -- | 1 | -- | -- |
Turn Signal/Multifunction Switch Ground | -- | 4 | -- | -- |
1. Headlamp Malfunction - Low Beam 2. Headlamp Malfunction - High Beam 3. Headlamp Switch Malfunction 4. Dimmer Switch Malfunction | ||||
Circuit/System Description
When the Headlamp switch is placed in the headlamp ON position, ground is applied to the body control module (BCM) through the headlamp signal circuit. The BCM then applies ground to the HDLP relay control circuit closing the relay contacts, allowing voltage to be applied to the RH HDLP and LH HDLP voltage supply circuits. Ground is applied at the HI/LO BEAM relay at all times with the headlamp dimmer switch in the LO BEAM position completing the circuit to the headlamps. Ground for the left headlamp and right headlamp is supplied at G102.
Conditions for Running the DTC
The battery voltage must be between 9-16 volts.
Conditions for Setting the DTC
The headlamp relay control circuit is shorted to voltage.
Action Taken When the DTC Sets
Both headlamps will be on at all times.
Conditions for Clearing the DTC
| • | This DTC will clear on current status after the condition for setting the fault is corrected and the ignition is cycled. |
| • | A history DTC will clear after 100 consecutive ignition cycles without a fault present. |
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 Verification
Ignition ON, command the headlamps ON and OFF with a scan tool. The headlamps should turn ON and OFF.
| ⇒ | If the headlamps do not turn ON, or remain always ON, perform the Headlamp CIrcuit/System Test.. |
Circuit/System Testing
- Ignition OFF, disconnect the HDLP relay.
- Connect a test lamp between the control circuit terminal 86 and the B+ circuit terminal 85.
- Ignition ON, command the low 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 HDLP 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, programming, and setup. |
