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U2955 Lost Communication with the Hybrid Powertrain Control Module (HPCM) A

The OBD2 code U2955 indicates a loss of communication with the Hybrid Powertrain Control Module (HPCM) A, suggesting that the vehicle's diagnostic system is unable to communicate with this specific module, which may...

Definition

The OBD2 code U2955 indicates a loss of communication with the Hybrid Powertrain Control Module (HPCM) A, suggesting that the vehicle's diagnostic system is unable to communicate with this specific module, which may affect hybrid system performance

Common causes

  • Faulty Hybrid Powertrain Control Module (HPCM)
  • Damaged or corroded wiring or connectors
  • Poor ground connections
  • Communication network issues (e.g., CAN bus problems)
  • Blown fuses
  • Faulty Engine Control Module (ECM)
  • Software or firmware issues in the HPCM or ECM
  • Battery issues affecting the HPCM operation

Common misdiagnoses

  • Faulty wiring or connectors
  • Defective Hybrid Powertrain Control Module (HPCM)
  • Issues with the Engine Control Module (ECM)
  • Battery or power supply problems
  • Faulty sensors related to the hybrid system
  • Communication issues with other control modules
  • Software or firmware issues in the HPCM or ECM

Troubleshooting steps

  1. 1. Check for Other Codes

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

  2. 2. Inspect the Wiring and Connectors

    Visual Inspection: Check the wiring harness and connectors related to the HPCM for any signs of damage, corrosion, or loose connections

  3. 3. Connector Pins

    Ensure that the pins in the connectors are not bent, corroded, or pushed back

  4. 4. Check Power and Ground

    Power Supply: Verify that the HPCM is receiving the correct voltage. Use a multimeter to check the power supply to the module

  5. 5. Ground Connections

    Ensure that the ground connections for the HPCM are secure and free of corrosion

  6. 6. Inspect the HPCM

    If possible, check the HPCM itself for any signs of physical damage or water intrusion

  7. 7. If the module is removable, consider reseating it to ensure a good connection

  8. 8. Check Communication Lines

    Use a scan tool to check the communication lines (CAN bus) for continuity and proper operation

  9. 9. Look for any shorts or opens in the communication lines that could be causing the loss of communication

  10. 10. Test the HPCM

    If you have access to a compatible scan tool, perform a functional test of the HPCM to see if it responds to commands

  11. 11. If the module is not responding, it may need to be replaced

  12. 12. Check for Software Updates

    Sometimes, manufacturers release software updates for the HPCM. Check with the manufacturer or a dealership to see if there are any updates available

  13. 13. Inspect Related Modules

    Since communication issues can sometimes be caused by other modules on the network, check for issues with other control modules that communicate with the HPCM

  14. 14. Clear Codes and Test Drive

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

  15. 15. Consult Technical Service Bulletins (TSBs)

    Look for any TSBs related to the HPCM or communication issues for your specific vehicle make and model. These can provide valuable insights and solutions.1

  16. 16. Professional Diagnosis

    If the issue persists after performing these steps, it may be necessary to consult a professional mechanic or dealership for further diagnosis. By following these steps, you should be able to identify the cause of the U2955 code and take appropriate action to resolve the communication issue with the Hybrid Powertrain Control Module