WOMS
P code powertrain Medium severity

P28AD Transmission Control Module (TCM) Performance

The OBD2 code P28AD 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 P28AD 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 level or poor fluid condition
  • 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  • Software issues or outdated TCM programming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
  • Poor ground connections

Common misdiagnoses

  • Faulty Transmission Control Module (TCM)
  • Wiring issues or short circuits
  • Faulty sensors (e.g., speed sensors)
  • Low transmission fluid levels
  • Transmission fluid contamination
  • Mechanical transmission issues
  • Engine control module (ECM) problems
  • Incorrectly calibrated transmission
  • Software issues or outdated firmware
  • Electrical connector problems

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 leading 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 cause performance issues

  7. 7. If the fluid is burnt or contaminated, consider changing it

  8. 8. Battery and Ground Connections

  9. 9. Ensure that the vehicle's battery is in good condition and fully charged

  10. 10. Check the ground connections for the TCM and other related components to ensure they are clean and secure

  11. 11. Perform a TCM Reset

  12. 12. Sometimes, resetting the TCM can clear temporary issues. This can be done by disconnecting the battery for a few minutes or using a scan tool to clear the code

  13. 13. Check for Software Updates

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

  15. 15. Inspect for Mechanical Issues

  16. 16. Check the transmission for any mechanical problems, such as slipping, unusual noises, or overheating, which could affect TCM performance

  17. 17. Test TCM Functionality

  18. 18. If possible, use a scan tool to monitor TCM data and performance parameters. Look for any abnormal readings that could indicate a malfunction

  19. 19. Check Input/Output Sensors

  20. 20. Inspect and test the input and output speed sensors, throttle position sensor, and other related sensors that provide data to the TCM

  21. 21. Consult Technical Service Bulletins (TSBs)

  22. 22. Look for any TSBs related to the specific make and model of the vehicle. Manufacturers may have issued guidance for addressing this code. 1

  23. 23. Consider Professional Diagnosis

  24. 24. If the issue persists after performing the above steps, it may be necessary to consult a professional mechanic or technician who has experience with transmission control systems. By following these steps, you can systematically diagnose and potentially resolve the issue associated with the P28AD code. Always refer to the vehicle's service manual for specific procedures and specifications related to your vehicle