WOMS
P code powertrain Medium severity

P1858 Transmission Transfer Case Contact Plate 'D' Circuit Failure

The OBD2 code P1858 indicates a failure in the 'D' circuit of the transmission transfer case contact plate, which typically involves issues with the electrical connections or components related to the transfer case's...

Definition

The OBD2 code P1858 indicates a failure in the 'D' circuit of the transmission transfer case contact plate, which typically involves issues with the electrical connections or components related to the transfer case's operation

Common causes

  • Faulty contact plate
  • Damaged wiring or connectors
  • Poor electrical connections
  • Short circuit in the circuit
  • Corrosion or dirt on connectors
  • Failed transfer case control module
  • Software issues in the vehicle's control module

Common misdiagnoses

  • Faulty transmission control module (TCM)
  • Wiring issues or shorts in the circuit
  • Defective transfer case motor
  • Malfunctioning transfer case control module
  • Incorrectly diagnosed transmission issues
  • Faulty sensors related to the transfer case
  • Battery or electrical system problems affecting the circuit

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 Wiring and Connectors

    Visually inspect the wiring and connectors associated with the transfer case contact plate. Look for

  3. 3. Damaged, frayed, or corroded wires

  4. 4. Loose or disconnected connectors

  5. 5. Signs of moisture or dirt that could affect connections

  6. 6. Test the Contact Plate

    If accessible, test the contact plate itself for continuity and proper operation. This may involve

  7. 7. Checking resistance across the terminals

  8. 8. Ensuring that the contact plate is not physically damaged

  9. 9. Check Power and Ground

    Verify that the contact plate is receiving the correct voltage and ground. Use a multimeter to check

  10. 10. Voltage at the connector when the vehicle is in the appropriate mode (e.g., ignition on)

  11. 11. Ground continuity to ensure a good connection

  12. 12. Inspect the Transfer Case Control Module

    If the wiring and contact plate are in good condition, the issue may lie with the transfer case control module. Check for

  13. 13. Faulty module operation

  14. 14. Software updates or reprogramming needs

  15. 15. Look for Mechanical Issues

    Inspect the transfer case for any mechanical issues that could affect the contact plate's operation. This includes

  16. 16. Checking for proper engagement and operation of the transfer case

  17. 17. Ensuring that there are no obstructions or damage within the transfer case

  18. 18. Clear Codes and Test Drive

    After performing the above checks and repairs, clear the trouble codes using the OBD-II scanner. Then, take the vehicle for a test drive to see if the code reappears

  19. 19. Seek Professional Help

    If the issue persists after performing these steps, it may be necessary to consult a professional mechanic or technician who has experience with your specific vehicle make and model. By following these troubleshooting steps, you can systematically identify and address the cause of the P1858 code