U1973 – Lost Communication with the Hybrid Powertrain Control Module (HPCM) A.

The ODBII code U1973 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 U1973 is typically considered moderate to severe.

Common Causes For: U1972 Control Module Communication Bus Off.

• Faulty Hybrid Powertrain Control Module (HPCM)
• Damaged or corroded wiring or connectors
• Failed communication network (CAN bus issues)
• Low battery voltage or weak battery
• Faulty Engine Control Module (ECM)
• Software issues or programming errors
• Grounding issues in the electrical system
• Intermittent electrical connections

Common misdiagnosis for U1973 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 the OBD-II code U1973, 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 Additional Codes: Use an OBD-II scanner to check for any other trouble codes that may be present. This can provide more context and help identify related issues.
• 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 damaged.
• Check Power and Ground: Verify that the HPCM is receiving the correct voltage and ground. Use a multimeter to check for proper voltage at the module’s power supply pins.
• Ensure that the ground connections are secure and free of corrosion.
• Test the HPCM: If possible, perform a functional test of the HPCM. This may require specialized diagnostic equipment or software.
• If the module is suspected to be faulty, consider replacing it or testing it in another vehicle if available.
• Inspect the CAN Bus: The HPCM communicates over the Controller Area Network (CAN) bus. Check for issues in the CAN bus wiring, such as shorts, opens, or interference.
• Use a scan tool to monitor the CAN bus for communication errors or abnormalities.
• Check for Software Updates: Verify if there are any software updates available for the HPCM or the vehicle’s ECU. Sometimes, manufacturers release updates to fix communication issues.
• Clear Codes and Test Drive: After performing the above checks and repairs, clear the trouble codes using the OBD-II scanner.
• Take the vehicle for a test drive to see if the code returns. Monitor the vehicle’s performance and any warning lights.
• Consult Technical Service Bulletins (TSBs): Check for any TSBs related to the specific make and model of the vehicle. Manufacturers may have issued bulletins regarding known issues with the HPCM.
• Seek Professional Help: If the issue persists after performing the above steps, it may be necessary to consult a professional mechanic or a dealership with experience in hybrid vehicles.Conclusion Troubleshooting OBD-II code U1973 involves a systematic approach to identify and resolve communication issues with the Hybrid Powertrain Control Module. By following these steps, you can narrow down the potential causes and take appropriate action to fix the problem.