WOMS
B code body Medium severity

B1240 Wiper Washer Rear Pump Relay Circuit Failure

The OBD2 code B1240 indicates a malfunction in the rear wiper washer pump relay circuit, which may involve issues such as a faulty relay, wiring problems, or a defective pump

Definition

The OBD2 code B1240 indicates a malfunction in the rear wiper washer pump relay circuit, which may involve issues such as a faulty relay, wiring problems, or a defective pump

Common causes

  • Faulty rear wiper washer pump relay
  • Damaged wiring or connectors in the relay circuit
  • Short circuit in the relay circuit
  • Open circuit in the relay circuit
  • Faulty rear wiper washer pump
  • Blown fuse related to the rear wiper washer system
  • Corrosion or poor connections in the relay or wiring
  • Malfunctioning body control module (BCM)

Common misdiagnoses

  • Faulty rear wiper motor
  • Bad wiper switch
  • Wiring issues or shorts in the harness
  • Defective body control module (BCM)
  • Low washer fluid level
  • Faulty front wiper relay
  • Incorrectly installed or damaged connectors

Troubleshooting steps

  1. 1. Check the Vehicle's Manual

    Refer to the vehicle's service manual for specific information regarding the rear wiper washer pump relay circuit, including wiring diagrams and component locations

  2. 2. Visual Inspection

    Inspect the wiring and connectors associated with the rear wiper washer pump relay. Look for signs of damage, corrosion, or loose connections

  3. 3. Check the relay itself for any physical damage

  4. 4. Test the Relay

    Remove the rear wiper washer pump relay and test it using a multimeter. You can also swap it with a similar relay in the fuse box (if applicable) to see if the problem persists

  5. 5. If the relay is faulty, replace it

  6. 6. Check the Fuse

    Locate the fuse associated with the rear wiper washer pump and check if it is blown. If it is, replace it and see if the issue is resolved

  7. 7. Inspect the Rear Washer Pump

    Test the rear washer pump for functionality. You can do this by applying direct power to the pump to see if it operates

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

  9. 9. Check for Ground Issues

    Ensure that the ground connection for the rear wiper washer pump relay is secure and free of corrosion. A poor ground can cause circuit failures

  10. 10. Examine the Control Circuit

    Use a multimeter to check for voltage at the relay connector when the rear washer is activated. If there is no voltage, trace back to the switch and wiring for issues

  11. 11. Check the switch that activates the rear washer to ensure it is functioning correctly

  12. 12. Scan for Additional Codes

    Use an OBD-II scanner to check for any additional trouble codes that may provide more context or indicate related issues

  13. 13. Consult Technical Resources

    If the problem persists, consult technical service bulletins (TSBs) or forums specific to your vehicle make and model for any known issues or fixes related to the B1240 code

  14. 14. Professional Diagnosis

    If you are unable to resolve the issue after these steps, consider seeking help from a professional mechanic who can perform more advanced diagnostics. By following these steps, you should be able to identify the cause of the B1240 code and take appropriate action to fix the issue