WOMS
B code body Medium severity

B1621 Wiper Rear Low Limit Input Circuit Short To Battery

The OBD2 code B1621 indicates a malfunction in the rear wiper system, specifically that the low limit input circuit is shorted to the battery, which means there is an electrical short causing the circuit to receive...

Definition

The OBD2 code B1621 indicates a malfunction in the rear wiper system, specifically that the low limit input circuit is shorted to the battery, which means there is an electrical short causing the circuit to receive constant power

Common causes

  • Shorted wiring or connectors
  • Faulty rear wiper motor
  • Malfunctioning wiper switch
  • Corroded or damaged electrical connections
  • Failed body control module (BCM)
  • Ground circuit issues

Common misdiagnoses

  • Faulty rear wiper motor
  • Damaged wiring or connectors
  • Malfunctioning body control module (BCM)
  • Incorrectly installed or defective wiper switch
  • Short circuit in the wiring harness
  • Faulty ground connection
  • Issues with the main fuse or relay for the wiper system

Troubleshooting steps

  1. 1. Visual Inspection

    Wiring and Connectors: Inspect the wiring harness and connectors related to the rear wiper motor and the low limit switch. Look for any signs of damage, fraying, or corrosion

  2. 2. Ground Connections

    Ensure that all ground connections are secure and free of corrosion

  3. 3. Check the Rear Wiper Motor

    Functionality: Test the rear wiper motor to ensure it operates correctly. If the motor is faulty, it may cause the circuit to short

  4. 4. Resistance Test

    Measure the resistance of the motor windings. If the resistance is too low, the motor may be shorted internally

  5. 5. Inspect the Low Limit Switch

    Functionality: Check the rear wiper low limit switch for proper operation. This switch is responsible for signaling the wiper control module when the wiper is in the "home" position

  6. 6. Continuity Test

    Use a multimeter to test for continuity in the switch. If it is stuck closed or open, it may need to be replaced

  7. 7. Check for Short Circuits

    Wiring Inspection: Look for any areas where the wiring may be pinched, frayed, or in contact with metal surfaces that could cause a short to battery

  8. 8. Multimeter Testing

    Use a multimeter to check for continuity between the low limit input circuit and battery voltage. If there is continuity, it indicates a short

  9. 9. Scan for Additional Codes

    OBD-II Scanner: Use an OBD-II scanner to check for any additional trouble codes that may provide more context to the issue. Addressing related codes may resolve the B1621 code

  10. 10. Check the Wiper Control Module

    Module Functionality: If all other components check out, the issue may lie within the wiper control module itself. Inspect for any signs of damage or failure

  11. 11. Reprogramming/Resetting

    In some cases, reprogramming or resetting the module may be necessary

  12. 12. Clear Codes and Test Drive

    After performing the necessary repairs, clear the trouble codes using the OBD-II scanner and take the vehicle for a test drive to see if the code returns

  13. 13. Seek Professional Help

    If you are unable to diagnose or fix the issue, consider seeking assistance from a qualified mechanic or automotive technician. By following these steps, you should be able to identify and resolve the issue associated with the B1621 code