2010 Cadillac Truck SRX AWD V6-3.0L Page 303
B258A 04
The BCM detects an open/high resistance in the headlamp low beam relay control circuit.
Action Taken When the DTC Sets
B258A 01 or B258A 04
The low beam headlamps will be inoperative.
B258A 02
The low beam headlamps will be continuously illuminated.
Conditions for Clearing the DTC
* The DTC will be current for as long as the fault is present.
* When the fault is no longer present, the DTC will be a history DTC.
* A history DTC will clear after 50 ignition cycles.
Reference Information
Schematic Reference
Headlights/Daytime Running Lights (DRL) Schematics (See: Diagrams/Electrical Diagrams/Lighting and Horns/System
Diagram/Headlights/Daytime Running Lights (DRL) Schematics)
Connector End View Reference
Component Connector End Views (See: Diagrams/Connector Views/Connector End Views By Name)
Description and Operation
Exterior Lighting Systems Description and Operation (See: Lighting and Horns/Description and Operation/Exterior Lighting Systems)
Electrical Information Reference
* Circuit Testing (See: Testing and Inspection/Component Tests and General Diagnostics/General Electrical Diagnostic Procedures/Circuit
Testing/Circuit Testing)
* Connector Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/General Electrical Diagnostic
Procedures/Connector Repairs/Connector Repairs)
* Testing for Intermittent Conditions and Poor Connections (See: Testing and Inspection/Component Tests and General Diagnostics/General
Electrical Diagnostic Procedures/Circuit Testing/Testing for Intermittent Conditions and Poor Connections)
* Wiring Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/General Electrical Diagnostic Procedures/Wiring
Repairs/Wiring Repairs)
Scan Tool Reference
Control Module References (See: Testing and Inspection/Programming and Relearning) for scan tool information
Circuit/System Verification
Ignition ON, command the Headlamp Low Beam ON and OFF with a scan tool. The low beam lamp should turn ON and OFF when changing
between the commanded states.
Circuit/System Testing
1. Ignition OFF, disconnect the KR49 headlamp low beam relay.
2. Ignition ON, verify that a test lamp does not illuminate between the control circuit terminal 30 and ground.
瀚慖f the test lamp illuminates, test the control circuit for a short to voltage
3. Verify that a test lamp illuminates between the B+ circuit terminal 87 and ground.
瀚慖f the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.
4. Verify that a test lamp illuminates between the B+ circuit terminal 86 and ground.
瀚慖f the test lamp does not illuminate, test the B+ circuit for an open/high resistance.
5. Connect a 15A fused jumper wire between the B+ circuit terminal 87 and the control circuit terminal 30. Verify the E4G headlamp-left low
beam and the E4H headlamp-right low beam are activated.
