WOMS
P code powertrain High severity

P28EE Transmission Control Module (TCM) Performance

The OBD2 code P28EE indicates that the Transmission Control Module (TCM) is experiencing performance issues, which may involve improper shifting, delayed engagement, or other transmission-related problems

Definition

The OBD2 code P28EE indicates that the Transmission Control Module (TCM) is experiencing performance issues, which may involve improper shifting, delayed engagement, or other transmission-related problems

Common causes

  • Faulty Transmission Control Module (TCM)
  • Wiring issues or damaged connectors
  • Low transmission fluid levels
  • Contaminated or degraded transmission fluid
  • Faulty transmission sensors (e.g., speed sensors)
  • Software issues or outdated TCM programming
  • Mechanical transmission problems
  • Electrical issues, such as short circuits or open circuits in the TCM circuit

Common misdiagnoses

  • Faulty Transmission Control Module (TCM)
  • Wiring issues or short circuits in the TCM harness
  • Faulty transmission sensors (e.g., speed sensors)
  • Low transmission fluid levels or fluid quality issues
  • Malfunctioning throttle position sensor
  • Engine control module (ECM) issues
  • Incorrectly calibrated or programmed TCM
  • Mechanical transmission problems (e.g., slipping or binding)
  • Faulty solenoids or actuators in the transmission
  • Software glitches or updates needed in the TCM

Troubleshooting steps

  1. 1. Check for Additional Codes

    Use an OBD-II scanner to check for any other related trouble codes. Sometimes, multiple codes can provide more context about the issue

  2. 2. Inspect TCM Connections

  3. 3. Check the wiring and connectors to the TCM for any signs of damage, corrosion, or loose connections

  4. 4. Ensure that the connectors are securely attached

  5. 5. Inspect Transmission Fluid

  6. 6. Check the transmission fluid level and condition. Low or dirty fluid can affect transmission performance

  7. 7. If the fluid is burnt or contaminated, consider a fluid change

  8. 8. Battery and Charging System Check

  9. 9. Ensure the vehicle's battery is in good condition and fully charged. A weak battery can cause erratic TCM performance

  10. 10. Check the alternator and charging system to ensure they are functioning properly

  11. 11. Perform a Visual Inspection

  12. 12. Look for any obvious signs of damage or wear in the transmission and related components

  13. 13. Check for any leaks around the transmission

  14. 14. Test the TCM

  15. 15. If possible, perform a bench test on the TCM to ensure it is functioning correctly

  16. 16. Some vehicles may require specialized equipment to test the TCM

  17. 17. Check for Software Updates

  18. 18. Verify if there are any software updates available for the TCM. Manufacturers sometimes release updates to fix known issues

  19. 19. Inspect Sensors and Inputs

  20. 20. Check the input signals to the TCM from various sensors (e.g., throttle position sensor, vehicle speed sensor, etc.) to ensure they are functioning correctly

  21. 21. Test the sensors for proper operation and replace any that are faulty

  22. 22. Clear Codes and Test Drive

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

  24. 24. Consult Technical Service Bulletins (TSBs)

  25. 25. Check for any TSBs related to the P28EE code for your specific vehicle make and model. Manufacturers may have specific recommendations or known issues. 1

  26. 26. Professional Diagnosis

  27. 27. If the issue persists after performing the above steps, consider seeking help from a professional mechanic or a dealership with experience in diagnosing transmission issues. By following these steps, you can systematically identify and address the cause of the P28EE code. Always refer to the vehicle's service manual for specific procedures and specifications related to your vehicle