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U code network High severity

U1943 Lost Communication with the Hybrid Powertrain Control Module (HPCM) A

The OBD2 code U1943 indicates a loss of communication with the Hybrid Powertrain Control Module (HPCM) A, which may affect the vehicle's hybrid system functionality

Definition

The OBD2 code U1943 indicates a loss of communication with the Hybrid Powertrain Control Module (HPCM) A, which may affect the vehicle's hybrid system functionality

Common causes

  • Faulty Hybrid Powertrain Control Module (HPCM)
  • Damaged or corroded wiring or connectors
  • Poor ground connections
  • Faulty communication network (CAN bus issues)
  • Blown fuses
  • Malfunctioning other related control modules
  • Software issues or programming errors

Common misdiagnoses

  • Faulty Hybrid Powertrain Control Module (HPCM)
  • Wiring issues or damaged connectors
  • Faulty Engine Control Module (ECM)
  • Battery management system problems
  • Issues with the vehicle's communication network (CAN bus)
  • Faulty sensors related to the hybrid system
  • Power supply issues to the HPCM
  • 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, other codes can provide context or indicate related issues

  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 damaged

  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 visible signs of damage or failure. This may include checking for burnt components or water intrusion

  7. 7. Check Communication Lines

    CAN Bus: Since the HPCM communicates over the CAN bus, check the CAN bus wiring for continuity and shorts. Use an oscilloscope or a CAN bus analyzer if available

  8. 8. Termination Resistors

    Ensure that the CAN bus termination resistors are present and functioning correctly

  9. 9. 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

  10. 10. If possible, compare the HPCM with a known good unit to rule out module failure

  11. 11. Check for Software Updates

    Sometimes, software issues can cause communication problems. Check with the manufacturer for any available updates for the HPCM or the vehicle’s ECU

  12. 12. Inspect Related Modules

    Since the HPCM communicates with other modules, check for communication issues with those modules as well. A fault in another module can sometimes cause communication issues with the HPCM

  13. 13. 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

  14. 14. Consult Technical Service Bulletins (TSBs)

    Look for any TSBs related to the specific make and model of the vehicle. Manufacturers may have issued guidance on common issues related to the HPCM.1

  15. 15. Professional Diagnosis

    If the issue persists after performing these steps, it may be necessary to consult a professional technician or dealership for further diagnosis. By following these steps, you should be able to identify the root cause of the U1943 code and take appropriate action to resolve the communication issue with the Hybrid Powertrain Control Module