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C1117 RPM Input Circuit Failure

The OBD2 code C1117 indicates a failure in the RPM input circuit, which means there is a problem with the signal or connection related to the engine's RPM readings

Definition

The OBD2 code C1117 indicates a failure in the RPM input circuit, which means there is a problem with the signal or connection related to the engine's RPM readings

Common causes

  • Faulty RPM sensor
  • Damaged wiring or connectors
  • Poor electrical connections
  • Malfunctioning engine control module (ECM)
  • Issues with the vehicle's powertrain control module (PCM)
  • Corroded or shorted circuits
  • Incorrectly installed or defective aftermarket parts
  • Mechanical issues affecting the engine's RPM readings

Common misdiagnoses

  • Faulty Engine Control Module (ECM)
  • Bad Crankshaft Position Sensor
  • Defective Camshaft Position Sensor
  • Wiring issues or shorts in the RPM input circuit
  • Faulty Transmission Control Module (TCM)
  • Incorrectly calibrated or malfunctioning throttle position sensor
  • Issues with the vehicle's battery or charging system
  • Problems with the ignition system

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 Wiring and Connectors

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

  4. 4. Pay special attention to the wiring harness leading to the engine speed sensor

  5. 5. Test the Engine Speed Sensor

  6. 6. Locate the engine speed sensor (often referred to as the crankshaft position sensor or camshaft position sensor)

  7. 7. Use a multimeter to test the sensor's resistance and output voltage according to the manufacturer's specifications

  8. 8. If the sensor is faulty, replace it

  9. 9. Check the Power and Ground

  10. 10. Ensure that the engine speed sensor is receiving the proper voltage and has a good ground connection

  11. 11. Use a multimeter to check for power at the sensor connector while the ignition is on

  12. 12. Inspect the PCM (Powertrain Control Module)

  13. 13. In some cases, the issue may be related to the PCM. Check for any signs of damage or corrosion

  14. 14. If necessary, perform a software update or reprogram the PCM according to the manufacturer's guidelines

  15. 15. Check for Short Circuits or Open Circuits

  16. 16. Use a multimeter to check for continuity in the wiring between the engine speed sensor and the PCM

  17. 17. Look for any short circuits to ground or open circuits that could be causing the failure

  18. 18. Clear the Codes and Test Drive

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

  20. 20. Take the vehicle for a test drive to see if the code reappears

  21. 21. Seek Professional Help

    If you are unable to diagnose or fix the issue, consider taking the vehicle to a qualified mechanic or dealership for further diagnosis. By following these steps, you should be able to identify and resolve the cause of the C1117 code