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U code network High severity

U2123 Lost Communication with Vehicle Dynamics Control Module

The OBD2 code U2123 indicates that there is a loss of communication between the vehicle's control module and the Vehicle Dynamics Control Module, which may affect systems related to stability and traction control

Definition

The OBD2 code U2123 indicates that there is a loss of communication between the vehicle's control module and the Vehicle Dynamics Control Module, which may affect systems related to stability and traction control

Common causes

  • Faulty Vehicle Dynamics Control Module (VDCM)
  • Damaged or corroded wiring or connectors
  • Poor ground connection
  • Faulty communication network (CAN bus issues)
  • Software or firmware issues in the VDCM
  • Malfunctioning other related modules
  • Low battery voltage or power supply issues

Common misdiagnoses

  • Faulty Vehicle Dynamics Control Module
  • Wiring issues or damaged connectors
  • Faulty ABS module
  • Malfunctioning Engine Control Module (ECM)
  • Incorrectly diagnosed wheel speed sensors
  • Power supply issues or blown fuses
  • Software or firmware issues in the control modules
  • Faulty body control module (BCM)

Troubleshooting steps

  1. 1. Check for Other Codes

    Use an OBD-II scanner to check for any additional trouble codes. Other codes may provide more context or indicate related issues

  2. 2. Inspect Wiring and Connectors

    Visual Inspection: Check the wiring harness and connectors related to the Vehicle Dynamics Control Module 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

    Verify that the Vehicle Dynamics Control Module is receiving proper power and ground. Use a multimeter to check voltage at the module's power supply pins

  5. 5. Check the ground connections to ensure they are secure and free of corrosion

  6. 6. Test the Vehicle Dynamics Control Module

    If possible, perform a functional test of the Vehicle Dynamics Control Module. This may involve using specialized diagnostic equipment or software

  7. 7. If the module is suspected to be faulty, consider replacing it or testing it in another vehicle if available

  8. 8. Inspect the CAN Bus

    The communication between modules typically occurs over the Controller Area Network (CAN) bus. Check for any issues with the CAN bus wiring, such as shorts, opens, or interference

  9. 9. Use an oscilloscope or CAN bus diagnostic tool to monitor the communication signals on the bus

  10. 10. Check for Software Updates

    Sometimes, communication issues can be resolved with a software update. Check with the vehicle manufacturer for any available updates for the ECM or VDCM

  11. 11. Clear Codes and Test Drive

    After performing the above checks and repairs, clear the trouble codes using the OBD-II scanner and take the vehicle for a test drive to see if the code returns

  12. 12. 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 U2123 code

  13. 13. Seek Professional Help

    If the issue persists after performing the above steps, it may be necessary to consult a professional mechanic or technician who has experience with the specific vehicle and its systems. By following these troubleshooting steps, you should be able to identify and resolve the issue causing the U2123 code