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B codebodyMedium severity

B1985Seat Switch Lumbar Deflate Circuit Failure

The OBD2 code B1985 indicates a malfunction in the lumbar deflate circuit of the seat switch, which may prevent the lumbar support from deflating properly

Definition

The OBD2 code B1985 indicates a malfunction in the lumbar deflate circuit of the seat switch, which may prevent the lumbar support from deflating properly

Common causes

  • Faulty seat switch
  • Damaged wiring or connectors
  • Short circuit in the lumbar deflate circuit
  • Failed lumbar support actuator
  • Poor ground connection
  • Corrosion in electrical connections
  • Malfunctioning control module

Common misdiagnoses

  • Faulty seat switch
  • Wiring issues or shorts in the seat harness
  • Defective lumbar support actuator
  • Malfunctioning body control module (BCM)
  • Incorrectly calibrated seat position sensors
  • Issues with the power supply to the seat system
  • Software glitches in the vehicle's control modules

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 multiple issues

  2. 2.Inspect the Seat Switch

  3. 3.Remove the seat cover or access panel to inspect the lumbar support switch

  4. 4.Check for any visible damage, corrosion, or loose connections at the switch

  5. 5.Test the Lumbar Support Switch

  6. 6.Use a multimeter to test the switch for continuity. Ensure that it operates correctly when pressed

  7. 7.If the switch is faulty, it may need to be replaced

  8. 8.Check Wiring and Connectors

  9. 9.Inspect the wiring harness and connectors leading to the lumbar support motor and switch for any signs of damage, fraying, or corrosion

  10. 10.Repair or replace any damaged wiring or connectors

  11. 11.Test the Lumbar Support Motor

  12. 12.If the switch and wiring are in good condition, test the lumbar support motor itself

  13. 13.Apply direct power to the motor to see if it operates. If it does not, the motor may be faulty and require replacement

  14. 14.Inspect the Control Module

  15. 15.If all components appear to be functioning correctly, the issue may lie within the vehicle's control module

  16. 16.Check for software updates or reprogramming needs, as sometimes a reset can resolve communication issues

  17. 17.Clear Codes and Test Drive

  18. 18.After performing repairs or replacements, clear the trouble codes using the OBD-II scanner

  19. 19.Take the vehicle for a test drive to see if the code returns

  20. 20.Refer to the vehicle's service manual for specific diagnostic procedures and wiring diagrams related to the lumbar support system

  21. 21.Seek Professional Help

  22. 22.If the issue persists after performing these steps, it may be best to consult a professional mechanic or dealership for further diagnosis. By following these steps, you should be able to identify and resolve the issue related to the B1985 code