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C codechassisMedium severity

C1859PRNDL Input #2 Circuit Failure

The OBD2 code C1859 indicates a malfunction in the PRNDL (Park, Reverse, Neutral, Drive, Low) input circuit #2, which affects the transmission's ability to determine the gear selection position

Definition

The OBD2 code C1859 indicates a malfunction in the PRNDL (Park, Reverse, Neutral, Drive, Low) input circuit #2, which affects the transmission's ability to determine the gear selection position

Common causes

  • Faulty PRNDL switch
  • Damaged wiring or connectors
  • Short circuit in the circuit
  • Open circuit in the circuit
  • Faulty transmission control module (TCM)
  • Corroded terminals
  • Poor ground connection
  • Malfunctioning gear selector assembly

Common misdiagnoses

  • Transmission Control Module (TCM) failure
  • Faulty PRNDL switch
  • Wiring issues or shorts in the circuit
  • Malfunctioning gear selector
  • Defective transmission range sensor
  • Issues with the vehicle's body control module (BCM)
  • Incorrectly calibrated or faulty speed sensors
  • Problems with the engine control module (ECM)
  • Low transmission fluid levels or quality
  • Faulty connectors or terminals in 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 other issues present

  2. 2.Inspect Wiring and Connectors

  3. 3.Visually inspect the wiring and connectors associated with the PRNDL switch. Look for signs of damage, corrosion, or loose connections

  4. 4.Pay special attention to the wiring harness that connects to the transmission range sensor

  5. 5.Test the PRNDL Switch

  6. 6.Use a multimeter to test the PRNDL switch for proper operation. Check for continuity in the switch when it is in different positions (Park, Reverse, Neutral, Drive)

  7. 7.Compare the readings to the specifications provided in the vehicle's service manual

  8. 8.Check for Ground Issues

    Ensure that the ground connections for the PRNDL switch and related components are secure and free of corrosion

  9. 9.Inspect the Transmission Control Module (TCM)

  10. 10.Check for any issues with the TCM, as it may not be interpreting the signals from the PRNDL switch correctly

  11. 11.Ensure that the TCM is receiving power and ground as required

  12. 12.Look for Mechanical Issues

  13. 13.Inspect the gear selector mechanism for any binding or mechanical issues that could prevent the PRNDL switch from functioning correctly

  14. 14.Ensure that the gear selector is properly aligned and not obstructed

  15. 15.Clear the Code and Test Drive

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

  16. 16.Consult the Service Manual

    If the issue persists, refer to the vehicle's service manual for specific diagnostic procedures and specifications related to the PRNDL input circuit

  17. 17.Seek Professional Help

    If you are unable to resolve the issue after performing these steps, it may be best to consult a professional mechanic or technician who has experience with transmission systems and OBD-II diagnostics. By following these troubleshooting steps, you should be able to identify and address the cause of the C1859 code