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 B2575 01: Headlamp Control Circuit Short to BatteryDTC B2575 06: Headlamp Control Circuit Short to Short to Ground or Open
Diagnostic Fault Information
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
|---|---|---|---|---|
Headlamp High Beam Relay B+ | 1 | 1 | -- | -- |
Headlamp Low Beam Relay B+ | 1 | 1 | -- | -- |
Ambient Light Senor Signal | B2645 02 | B2645 05 | B2645 01 | -- |
Flash to Pass Switch Signal | 1 | 1 | 1 | -- |
DRL Relay Control | B2600 00 | B2600 00 | 2 | -- |
Headlamp High Beam Relay Control | B2580 06 | B2580 06 | B2580 01 | -- |
Headlamp Low Beam Relay Control | B2575 06 | B2575 06 | B2575 01 | -- |
LF Low Beam Headlamp Control | 1 | 1 | 1 | -- |
RF Low Beam Headlamp Control | 1 | 1 | 1 | -- |
Ambient Light Senor Low Reference | -- | 2 | 2 | -- |
LF Headlamp Ground | -- | 1 | -- | -- |
RF Headlamp Ground | -- | 1 | -- | -- |
Turn Signal/Multifunction Switch Ground | -- | 1 | -- | -- |
1. Headlamps Malfunction 2. Daytime Running Lamps Malfunction | ||||
Circuit/System Description
Battery positive voltage is applied at all times to both the coil and switch sides of the Low Beam relay located in the underhood fuse block. When the turn signal/multifunction switch is placed in the headlamp position, ground is applied to the body control module (BCM) through the headlamp low beam signal circuit. The BCM then applies ground to the headlamp low beam relay control circuit which energizes the low beam relay. With the low beam relay energized, the switch contacts close allowing battery voltage to flow through the LOW BEAM fuses to the low beam headlamps. Ground for the left headlamp is supplied at G101 and the right headlamp receives ground at G102.
Conditions for Running the DTC
| • | Battery voltage must be between 9-16 volts. |
| • | Headlamps ON. |
Conditions for Setting the DTC
B2575 01
The DTC will set when the BCM detects a short to voltage in the low beam relay control circuit.
B2575 06
The DTC will set when the BCM detects a short to ground or an open in the low beam relay control circuit.
Action Taken When the DTC Sets
| • | When DTC B2575 01 is present, the low beam headlamps will not operate. |
| • | When DTC B2575 06 is present, the low beam headlamps will be ON at all times or 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
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 low beam relay.
- Connect a test lamp between the control circuit terminal 86 and the B+ circuit terminal 85.
- Command the 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 low 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 an 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 |
