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

The ODBII 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.

The severity of ODBII code U2955 is typically considered moderate to severe.

Common Causes For: U2954 U2954: “Vehicle Communication Bus Malfunction”

• 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 misdiagnosis for U2955 Lost Communication with the Hybrid Powertrain Control Module (HPCM) A.

• 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

Common Troubleshooting Steps

When dealing with OBD-II code U2955, which indicates “Lost Communication with the Hybrid Powertrain Control Module (HPCM) A,” there are several common troubleshooting steps you can follow to diagnose and potentially resolve the issue. Here’s a structured approach:

• 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.
• 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.
• **Connector Pins: Ensure that the pins in the connectors are not bent, corroded, or pushed back.
• 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.
• **Ground Connections: Ensure that the ground connections for the HPCM are secure and free of corrosion.
• Inspect the HPCM: If possible, check the HPCM itself for any signs of physical damage or water intrusion.
• If the module is removable, consider reseating it to ensure a good connection.
• Check Communication Lines: Use a scan tool to check the communication lines (CAN bus) for continuity and proper operation.
• Look for any shorts or opens in the communication lines that could be causing the loss of communication.
• 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.
• If the module is not responding, it may need to be replaced.
• 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.
• 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.
• 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.
• 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
• 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.