WOMS
P code powertrain Medium severity

P1566 Speed Control Command Switch Out of Range Low

The OBD2 code P1566 indicates that the speed control command switch is sending a signal that is lower than the expected range, which may affect the operation of the cruise control system

Definition

The OBD2 code P1566 indicates that the speed control command switch is sending a signal that is lower than the expected range, which may affect the operation of the cruise control system

Common causes

  • Faulty speed control command switch
  • Wiring issues or damaged connectors
  • Malfunctioning throttle position sensor
  • Faulty cruise control module
  • Software or calibration issues in the engine control module (ECM)
  • Vacuum leaks in the throttle body or intake system
  • Electrical shorts or open circuits in the speed control system

Common misdiagnoses

  • Throttle position sensor issues
  • Accelerator pedal position sensor problems
  • Cruise control module failure
  • Wiring or connector issues
  • Engine control module (ECM) faults
  • Vacuum leaks
  • Faulty brake light switch
  • Malfunctioning speed sensor

Troubleshooting steps

  1. 1. Check for Additional Codes

    Use an OBD-II scanner to check for any other trouble codes that may be present. Addressing any related codes can help in diagnosing the issue

  2. 2. Inspect the Cruise Control Switch

  3. 3. Check the cruise control switch for any physical damage or wear

  4. 4. Ensure that the switch is functioning properly. You can test the switch with a multimeter to see if it is sending the correct signals when pressed

  5. 5. Examine Wiring and Connectors

  6. 6. Inspect the wiring harness and connectors associated with the cruise control system for any signs of damage, corrosion, or loose connections

  7. 7. Repair or replace any damaged wiring or connectors

  8. 8. Check the Brake Pedal Position Switch

  9. 9. The brake pedal position switch can affect the cruise control operation. Ensure that it is functioning correctly and that the brake lights are working as intended

  10. 10. If the switch is faulty, it may need to be adjusted or replaced

  11. 11. Inspect the Throttle Position Sensor (TPS)

  12. 12. The TPS provides input to the engine control module (ECM) regarding the position of the throttle. If it is malfunctioning, it can cause issues with the cruise control system

  13. 13. Test the TPS with a multimeter to ensure it is providing the correct voltage readings

  14. 14. Check the Vehicle Speed Sensor (VSS)

  15. 15. The VSS provides speed information to the ECM. If it is faulty, it can lead to incorrect readings and affect the cruise control operation

  16. 16. Test the VSS to ensure it is functioning properly

  17. 17. Examine the Engine Control Module (ECM)

  18. 18. In some cases, the ECM may be at fault. Check for any software updates or reprogramming that may be necessary

  19. 19. If all other components check out, consider having the ECM tested or replaced

  20. 20. Clear the Codes and Test Drive

  21. 21. After performing the necessary repairs, clear the trouble codes using the OBD-II scanner

  22. 22. Take the vehicle for a test drive to see if the code returns and if the cruise control system operates correctly

  23. 23. Consult a Professional

  24. 24. If you are unable to resolve the issue after these steps, it may be best to consult a professional mechanic or technician who has experience with cruise control systems. By following these troubleshooting steps, you should be able to identify and resolve the issue related to the P1566 code