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P code powertrain High severity

P1857 Transmission Transfer Case Contact Plate 'C' Short Circuit To Ground

The OBD2 code P1857 indicates a short circuit to ground in the transmission transfer case contact plate 'C', which typically affects the transfer case's ability to communicate or function properly

Definition

The OBD2 code P1857 indicates a short circuit to ground in the transmission transfer case contact plate 'C', which typically affects the transfer case's ability to communicate or function properly

Common causes

  • Damaged wiring or connectors
  • Faulty transfer case contact plate
  • Short circuit in the wiring harness
  • Corroded connectors
  • Water intrusion or moisture in the electrical system
  • Malfunctioning control module
  • Poor ground connections

Common misdiagnoses

  • Faulty transfer case control module
  • Wiring issues or damaged harness
  • Faulty transfer case motor
  • Incorrectly diagnosed transmission issues
  • Battery or electrical system problems
  • Faulty sensors unrelated to the transfer case
  • Software or calibration issues in the vehicle's ECU

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 harness and connectors associated with the transfer case contact plate. Look for signs of damage, such as frayed wires, corrosion, or loose connections

  3. 3. Pay special attention to the wiring that leads to the contact plate 'C'

  4. 4. Test the Contact Plate

    If accessible, test the contact plate itself for continuity and resistance. Use a multimeter to check for shorts to ground

  5. 5. Compare the readings with the specifications provided in the vehicle’s service manual

  6. 6. Check for Ground Issues

    Inspect the ground connections related to the transfer case. A poor ground can cause electrical issues, including short circuits

  7. 7. Clean and secure any corroded or loose ground connections

  8. 8. Inspect the Transfer Case

    If the wiring and connectors are in good condition, inspect the transfer case for any internal issues that may be causing the short circuit

  9. 9. Look for signs of fluid leaks or damage to the transfer case housing

  10. 10. Check for Shorts in the Circuit

    Use a multimeter to check for shorts in the circuit. Disconnect the battery and perform a continuity test on the wiring to see if there are any unintended connections to ground

  11. 11. Clear the Code and Test Drive

    After performing the above checks and repairs, clear the trouble code using the OBD-II scanner

  12. 12. Take the vehicle for a test drive to see if the code reappears. Monitor the vehicle's performance during the drive

  13. 13. Consult a Professional

    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

  14. 14. Refer to Service Manual

    Always refer to the vehicle’s service manual for specific diagnostic procedures, wiring diagrams, and specifications related to the transfer case and contact plate. By following these troubleshooting steps, you should be able to identify and resolve the issue related to the P1857 code