WOMS
B code body Medium severity

B1508 Flash To Pass Switch Circuit Open

The OBD2 code B1508 indicates that there is an open circuit in the Flash To Pass switch, which is responsible for activating the high beam headlights momentarily

Definition

The OBD2 code B1508 indicates that there is an open circuit in the Flash To Pass switch, which is responsible for activating the high beam headlights momentarily

Common causes

  • Faulty flash to pass switch
  • Open circuit in wiring
  • Poor connections or corroded terminals
  • Malfunctioning body control module (BCM)
  • Blown fuse related to the lighting system
  • Short circuit in the wiring harness

Common misdiagnoses

  • Faulty headlight switch
  • Bad wiring or connectors
  • Malfunctioning body control module (BCM)
  • Defective multifunction switch
  • Issues with the relay or fuse
  • Incorrectly diagnosed as a battery or charging system problem
  • Misinterpretation as a problem with the headlights themselves

Troubleshooting steps

  1. 1. Check for Additional Codes

    Use an OBD-II scanner to check for any other related trouble codes. This can provide more context and help identify if there are other issues present

  2. 2. Inspect the Flash To Pass Switch

    Locate the flash-to-pass switch (usually integrated into the headlight control stalk)

  3. 3. Visually inspect the switch for any signs of damage, wear, or corrosion

  4. 4. Ensure that the switch is functioning properly by testing it manually

  5. 5. Test the Wiring and Connectors

    Inspect the wiring harness and connectors associated with the flash-to-pass switch for any signs of damage, fraying, or corrosion

  6. 6. Use a multimeter to check for continuity in the wiring. An open circuit may indicate a broken wire or poor connection

  7. 7. Check for Ground Issues

    Ensure that the ground connections related to the flash-to-pass switch are secure and free of corrosion

  8. 8. Test the ground circuit with a multimeter to ensure proper grounding

  9. 9. Examine the Body Control Module (BCM)

    The BCM may be responsible for processing the signal from the flash-to-pass switch. Check for any faults or issues with the BCM

  10. 10. If necessary, reprogram or replace the BCM, but this should be a last resort after other issues have been ruled out

  11. 11. Inspect Related Components

    Check other components that may be related to the headlight system, such as relays and fuses. A blown fuse or faulty relay could affect the operation of the flash-to-pass switch

  12. 12. Perform a Visual Inspection of the Headlight System

    Ensure that the headlights themselves are functioning properly. If there are issues with the headlights, it may affect the flash-to-pass feature

  13. 13. Clear the Code and Test Drive

    After performing the above checks and repairs, clear the trouble code using the OBD-II scanner

  14. 14. Take the vehicle for a test drive to see if the code reappears. If it does, further investigation may be needed

  15. 15. Consult a Professional

    If the issue persists after performing these troubleshooting steps, it may be best to consult a professional mechanic or technician who has experience with your specific vehicle make and model. By following these steps, you should be able to identify and resolve the issue related to the B1508 code. Always refer to the vehicle's service manual for specific diagnostic procedures and specifications