LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Chevrolet >> 2012 >> Traverse LS, AWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 8 (Lighting System) >> Diagnostic Information and Procedures >> DTC B258A >> Circuit/System Testing
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Circuit/System Testing

WARNING: This page is about a different car, the 2010 Cadillac SRX. However, it is still accessible from the selected car via links, so may be relevant.
  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.
    • If 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.
    • If 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.
    • If 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.
    • If the E4G headlamp-left low beam and the E4H headlamp-right low beam do not activate, test the control circuit for a short to ground or an open/high resistance.
  6. Connect a test lamp between the B+ circuit terminal 86 and the control circuit terminal 85.
  7. Ignition ON, 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 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 K9 BCM.
  8. If all circuits test normal, test or replace the KR49 headlamp low beam relay.
scientia non olet · About LEMON Manuals