WOMS
B code body Medium severity

B1818 Wiper Rear Motor Up Relay Coil Circuit Failure

The OBD2 code B1818 indicates a failure in the rear wiper motor up relay coil circuit, which may involve issues such as an open circuit, short circuit, or a malfunctioning relay affecting the operation of the rear wiper

Definition

The OBD2 code B1818 indicates a failure in the rear wiper motor up relay coil circuit, which may involve issues such as an open circuit, short circuit, or a malfunctioning relay affecting the operation of the rear wiper

Common causes

  • Faulty rear wiper motor
  • Damaged wiring or connectors
  • Failed relay
  • Short circuit in the circuit
  • Open circuit in the circuit
  • Corroded terminals
  • Faulty switch or control module
  • Grounding issues

Common misdiagnoses

  • Faulty rear wiper motor
  • Bad wiper switch
  • Wiring issues or shorts in the circuit
  • Defective relay
  • Poor ground connection
  • Malfunctioning body control module (BCM)
  • Incorrectly diagnosed front wiper issues

Troubleshooting steps

  1. 1. Check the Vehicle's Manual

    Refer to the vehicle's service manual for specific information regarding the rear wiper system and wiring diagrams

  2. 2. Visual Inspection

  3. 3. Inspect the wiring and connectors associated with the rear wiper motor and relay for any signs of damage, corrosion, or loose connections

  4. 4. Check the condition of the rear wiper motor itself

  5. 5. Test the Relay

  6. 6. Locate the rear wiper relay in the fuse box or relay panel

  7. 7. Swap the relay with a similar one (if available) to see if the problem persists

  8. 8. Use a multimeter to test the relay for continuity and proper operation

  9. 9. Check Fuses

  10. 10. Inspect the fuses related to the rear wiper system. Replace any blown fuses and check if the issue is resolved

  11. 11. Test the Wiper Motor

  12. 12. Disconnect the rear wiper motor and test it directly by applying power to see if it operates

  13. 13. If the motor does not work when powered directly, it may need to be replaced

  14. 14. Check for Ground Issues

  15. 15. Ensure that the rear wiper motor has a good ground connection. A poor ground can cause circuit failures

  16. 16. Inspect the Control Switch

  17. 17. Check the rear wiper switch on the dashboard for proper operation. A faulty switch can send incorrect signals to the relay

  18. 18. Scan for Additional Codes

  19. 19. Use an OBD-II scanner to check for any additional trouble codes that may provide more context to the issue

  20. 20. Check for Short Circuits

  21. 21. Inspect the wiring for any signs of short circuits or open circuits that could affect the relay coil circuit

  22. 22. Consult a Professional

  23. 23. If the issue persists after performing these steps, it may be best to consult a professional mechanic or technician for further diagnosis. By following these steps, you should be able to identify the cause of the B1818 code and take appropriate action to resolve the issue