B258A
DTC B258A
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions Diagnostic Procedure Instructions provides an overview of each diagnostic category.
DTC Descriptor
DTC B258A 01
-
Low Beam Control Circuit Short to Battery
Diagnostic Fault Information
Circuit/System Description
The headlamp low beam relay is supplied with battery voltage at all times. The headlamp switch signal circuit is grounded by turning the headlamp switch. The body control module (BCM) energizes the headlamp low beam relay by applying ground to the headlamp low beam relay control circuit. When the headlamp low beam relay is energized, the relay switch contacts close and battery voltage is applied through the low beam lamp fuses to the low beam lamp supply voltage circuit which illuminates the low beam lamps.
Conditions for Running the DTC
B258A 01 or B258A 04
The headlamp switch in low beam position.
B258A 02
The headlamp switch in OFF or AUTO position.
Conditions for Setting the DTC
B258A 01
The BCM detects a short to battery on the control circuit.
B258A 02
The BCM detects a short to ground on the control circuit.
B258A 04
The BCM detects an open control circuit.
Action Taken When the DTC Sets
Headlamp low beam malfunction.
Conditions for Clearing the DTC
The condition for setting the DTC is no longer present.
Reference Information
Schematic Reference
Headlights/Daytime Running Lights (DRL) Schematics Headlights/Daytime Running Lights (DRL) Schematics
Connector End View Reference
Component Connector End Views Sunshade - Left (DH6)
Description and Operation
Exterior Lighting Systems Description and Operation Exterior Lighting Systems
Electrical Information Reference
* Circuit Testing Circuit Testing
* Connector Repairs Connector Repairs
* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections
* Wiring Repairs Wiring Repairs
Scan Tool Reference
Control Module References Control Module References for scan tool information
Circuit/System Verification
Ignition ON, perform the appropriate Headlamp Low Beam Command test. The appropriate low beam lamp should be ON/OFF.
Circuit/System Testing
1. Ignition OFF, disconnect the X2 harness connector at the X50A Fuse Block - Underhood Primary.
2. Connect a test lamp between the B+ and the control circuit X50A Fuse Block - Underhood Primary terminal 42 X2.
3. Command the Low Beam Lamps 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.
4. If all circuits test normal, test or replace the X50A Fuse Block - Underhood Primary.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.
* Relay Replacement (Within an Electrical Center) Relay Replacement (Within an Electrical Center)Relay Replacement (Attached to Wire Harness) Relay Replacement (Attached to Wire Harness)
* Control Module References Control Module References for BCM replacement, setup and programming