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P1903 Pressure Control Solenoid "C" Short Circuit

The OBD2 code P1903 indicates a short circuit in the Pressure Control Solenoid "C," which affects the transmission's ability to regulate fluid pressure properly, potentially leading to shifting issues or transmission...

Definition

The OBD2 code P1903 indicates a short circuit in the Pressure Control Solenoid "C," which affects the transmission's ability to regulate fluid pressure properly, potentially leading to shifting issues or transmission performance problems

Common causes

  • Faulty pressure control solenoid "C"
  • Shorted wiring or connectors
  • Open circuit in the wiring
  • Corroded or damaged connectors
  • Faulty transmission control module (TCM)
  • Poor ground connection
  • Internal transmission failure

Common misdiagnoses

  • Faulty Transmission Control Module (TCM)
  • Wiring issues or shorts in the harness
  • Faulty Pressure Control Solenoid "A" or "B"
  • Low transmission fluid level or contamination
  • Faulty transmission valve body
  • Incorrectly installed or damaged connectors
  • Other solenoid or actuator failures
  • Transmission overheating issues
  • Faulty engine control module (ECM) or software issues
  • Mechanical transmission problems

Troubleshooting steps

  1. 1. Check the Vehicle's Service Manual

    Refer to the specific service manual for your vehicle to understand the wiring diagrams, solenoid specifications, and any specific procedures related to the P1903 code

  2. 2. Visual Inspection

  3. 3. Inspect the wiring harness and connectors associated with the pressure control solenoid "C" for any signs of damage, fraying, or corrosion

  4. 4. Look for any loose connections or broken wires that could cause a short circuit

  5. 5. Check the Solenoid

  6. 6. Test the pressure control solenoid "C" for proper operation. You can do this by measuring the resistance across the solenoid terminals with a multimeter. Compare the readings to the specifications in the service manual

  7. 7. If the solenoid is shorted (very low resistance or zero resistance), it may need to be replaced

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

  9. 9. Check for any signs of damage or corrosion in the PCM connectors

  10. 10. Ensure that the PCM is functioning correctly and that there are no other related codes present that could indicate a broader issue

  11. 11. Check for Short Circuits

  12. 12. Use a multimeter to check for continuity between the solenoid wiring and ground. If there is continuity where there shouldn't be, this indicates a short circuit

  13. 13. Inspect the wiring harness for any areas where the wires may be pinched or rubbing against metal surfaces

  14. 14. Test the Circuit

  15. 15. With the ignition on (engine off), use a multimeter to check for voltage at the solenoid connector. You should see the appropriate voltage as specified in the service manual

  16. 16. If there is no voltage, trace the wiring back to the PCM to identify any breaks or issues

  17. 17. Clear the Code and Test Drive

  18. 18. After performing repairs or replacements, clear the trouble codes using an OBD-II scanner

  19. 19. Take the vehicle for a test drive to see if the code returns. Monitor the transmission performance to ensure it operates correctly

  20. 20. Seek Professional Help

  21. 21. If the issue persists after following these steps, it may be necessary to consult a professional mechanic or technician who has experience with transmission issues and OBD-II diagnostics. By following these steps, you should be able to identify and resolve the issue related to the P1903 code. Always ensure safety precautions are taken when working on a vehicle's electrical system