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C1945 Park Switch Indicates Park with Vehicle Moving

The OBD2 code C1945 indicates that the park switch has detected that the vehicle is in the park position while it is still moving, which may suggest a malfunction in the transmission or park switch system

Definition

The OBD2 code C1945 indicates that the park switch has detected that the vehicle is in the park position while it is still moving, which may suggest a malfunction in the transmission or park switch system

Common causes

  • Faulty park switch
  • Wiring issues or shorts in the park switch circuit
  • Malfunctioning transmission control module (TCM)
  • Incorrectly adjusted or damaged transmission linkage
  • Faulty vehicle speed sensor
  • Software issues in the vehicle's control modules
  • Mechanical issues within the transmission

Common misdiagnoses

  • Faulty transmission range sensor
  • Defective park/neutral position switch
  • Malfunctioning brake light switch
  • Wiring issues or shorts in the harness
  • Faulty engine control module (ECM)
  • Incorrectly installed or damaged transmission components
  • Issues with the vehicle speed sensor
  • Problems with the anti-lock braking system (ABS) module

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 and help identify related issues

  2. 2. Inspect the Park Switch

  3. 3. Locate the park switch (often part of the transmission assembly) and inspect it for any physical damage or wear

  4. 4. Ensure that the switch is properly connected and that the wiring harness is intact without any frayed wires or corrosion

  5. 5. Test the Park Switch

  6. 6. Use a multimeter to test the park switch for continuity. It should show continuity when the vehicle is in the "Park" position and no continuity when in other positions

  7. 7. If the switch is faulty, it may need to be replaced

  8. 8. Check Transmission Linkage

  9. 9. Inspect the transmission linkage to ensure it is properly adjusted and functioning. Misalignment can cause incorrect signals to be sent to the park switch

  10. 10. Look for any obstructions or damage that may prevent the linkage from moving freely

  11. 11. Inspect the Vehicle Speed Sensor (VSS)

  12. 12. The vehicle speed sensor provides information about the vehicle's speed to the engine control module (ECM) and transmission control module (TCM). A malfunctioning VSS can cause incorrect readings and trigger the C1945 code

  13. 13. Test the VSS for proper operation and replace it if necessary

  14. 14. Check for Electrical Issues

  15. 15. Inspect the wiring and connectors related to the park switch and transmission for any signs of damage, corrosion, or loose connections

  16. 16. Use a wiring diagram to trace the circuit and ensure there are no breaks or shorts

  17. 17. Examine the Transmission Control Module (TCM)

  18. 18. If all other components check out, the issue may lie within the TCM itself. Check for software updates or reprogramming needs

  19. 19. In some cases, the TCM may need to be replaced if it is found to be faulty

  20. 20. Perform a Visual Inspection

  21. 21. Look for any signs of fluid leaks, especially around the transmission area, which could indicate a more significant issue

  22. 22. Clear Codes and Test Drive

  23. 23. After performing repairs or adjustments, clear the trouble codes and take the vehicle for a test drive to see if the code returns

  24. 24. Consult a Professional

  25. 25. If the issue persists after performing these steps, it may be best 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 and resolve the issue related to the C1945 code