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P1879 Transmission Transfer Case Disengaged Solenoid Open Circuit

The OBD2 code P1879 indicates that there is an open circuit in the transmission transfer case disengaged solenoid, which means the solenoid is not functioning properly or is not receiving power, potentially affecting...

Definition

The OBD2 code P1879 indicates that there is an open circuit in the transmission transfer case disengaged solenoid, which means the solenoid is not functioning properly or is not receiving power, potentially affecting the operation of the transfer case

Common causes

  • Faulty transmission control module (TCM)
  • Open or shorted wiring in the solenoid circuit
  • Defective transfer case disengaged solenoid
  • Poor electrical connections or corroded terminals
  • Malfunctioning transfer case
  • Low transmission fluid levels
  • Faulty vehicle speed sensor (VSS)

Common misdiagnoses

  • Faulty transmission control module (TCM)
  • Defective transfer case motor
  • Wiring issues or shorts in the harness
  • Faulty transfer case position sensor
  • Low transmission fluid levels
  • Malfunctioning shift solenoid
  • Incorrectly diagnosed transmission failure
  • Issues with the vehicle's computer or software glitches

Troubleshooting steps

  1. 1. Check for Additional Codes

    Use an OBD-II scanner to check for any other trouble codes that may be present. This can provide more context for the issue

  2. 2. Inspect Wiring and Connectors

    Visually inspect the wiring and connectors associated with the disengaged solenoid. Look for signs of damage, corrosion, or loose connections

  3. 3. Pay special attention to the harness leading to the transfer case and the solenoid itself

  4. 4. Test the Solenoid

    Use a multimeter to test the solenoid for continuity. If the solenoid is open (infinite resistance), it may need to be replaced

  5. 5. If possible, apply direct power to the solenoid to see if it activates. If it does not, the solenoid may be faulty

  6. 6. Check Power and Ground

    Verify that the solenoid is receiving the correct voltage and ground signal. Use a multimeter to check for power at the solenoid connector while the vehicle is in the appropriate mode (e.g., 4WD engaged)

  7. 7. If there is no power, trace the wiring back to the control module to identify any breaks or shorts

  8. 8. Inspect the Transfer Case Control Module

    If the wiring and solenoid are in good condition, the issue may lie within the transfer case control module. Check for any signs of damage or corrosion

  9. 9. If possible, test the module with a scan tool to see if it is functioning correctly

  10. 10. Check for Mechanical Issues

    Inspect the transfer case for any mechanical issues that could prevent the solenoid from functioning properly. This includes checking for proper fluid levels and any signs of internal damage

  11. 11. Clear Codes and Test Drive

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

  12. 12. 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 should be able to identify the cause of the P1879 code and take appropriate action to resolve the issue