WOMS
B code body Medium severity

B1593 Autolamp Delay Decrease Circuit Short To Battery

The OBD2 code B1593 indicates a short circuit in the autolamp delay decrease circuit, causing it to connect directly to the battery, which can affect the operation of the vehicle's automatic lighting system

Definition

The OBD2 code B1593 indicates a short circuit in the autolamp delay decrease circuit, causing it to connect directly to the battery, which can affect the operation of the vehicle's automatic lighting system

Common causes

  • Shorted wiring or connectors
  • Faulty autolamp control module
  • Corroded or damaged connectors
  • Malfunctioning relay
  • Incorrectly installed aftermarket accessories
  • Grounding issues
  • Faulty sensors or switches related to the autolamp system

Common misdiagnoses

  • Faulty headlight switch
  • Defective body control module (BCM)
  • Shorted wiring harness
  • Malfunctioning autolamp relay
  • Incorrectly installed aftermarket lighting
  • Battery issues or poor connections
  • Faulty sensors related to ambient light detection

Troubleshooting steps

  1. 1. Check the Vehicle's Manual

    Refer to the vehicle's service manual for specific information about the autolamp system and wiring diagrams

  2. 2. Visual Inspection

  3. 3. Inspect the wiring and connectors associated with the autolamp system for any signs of damage, corrosion, or loose connections

  4. 4. Look for any frayed wires or signs of wear that could cause a short circuit

  5. 5. Check Fuses

  6. 6. Locate and inspect the fuses related to the autolamp system. Replace any blown fuses and check if the code returns

  7. 7. Test the Autolamp Switch

  8. 8. Test the autolamp switch for proper operation. A faulty switch can cause incorrect signals to be sent to the control module

  9. 9. Use a Multimeter

  10. 10. With the ignition on, use a multimeter to check for voltage in the autolamp delay decrease circuit. Compare the readings to the specifications in the service manual

  11. 11. Check for continuity in the circuit to ensure there are no breaks

  12. 12. Check for Short Circuits

  13. 13. Inspect the wiring harness for any shorts to ground or battery. You can do this by disconnecting the battery and using the multimeter to check for continuity between the circuit and ground

  14. 14. Inspect the Body Control Module (BCM)

  15. 15. The BCM controls the autolamp system. If all other components check out, the BCM may be faulty. Check for any software updates or recalls related to the BCM

  16. 16. Clear the Code

  17. 17. After performing the checks and repairs, clear the code using an OBD-II scanner and take the vehicle for a test drive to see if the code returns

  18. 18. Professional Diagnosis

  19. 19. If the issue persists after performing these steps, it may be necessary to consult a professional mechanic or technician who can perform more advanced diagnostics. By following these steps, you should be able to identify and resolve the issue related to the B1593 code. Always ensure safety precautions are taken when working on electrical systems in vehicles