WOMS
U code network High severity

U1128 Lost Communication with Vehicle Dynamics Control Module

The OBD2 code U1128 indicates that there is a loss of communication between the vehicle's onboard computer and the Vehicle Dynamics Control Module, which may affect systems like traction control and stability control

Definition

The OBD2 code U1128 indicates that there is a loss of communication between the vehicle's onboard computer and the Vehicle Dynamics Control Module, which may affect systems like traction control and stability control

Common causes

  • Faulty Vehicle Dynamics Control Module (VDCM)
  • Damaged or corroded wiring or connectors
  • Poor ground connection
  • Faulty communication lines (CAN bus issues)
  • Malfunctioning sensors related to vehicle dynamics
  • Software or firmware issues in the VDCM
  • Battery or power supply issues affecting the VDCM
  • Interference from aftermarket modifications or devices

Common misdiagnoses

  • Faulty ABS module
  • Defective wheel speed sensors
  • Malfunctioning engine control module (ECM)
  • Wiring issues or damaged connectors
  • Faulty powertrain control module (PCM)
  • Incorrectly diagnosed brake system issues
  • Battery or charging system problems
  • Software or firmware issues in the vehicle's control modules

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 Vehicle Dynamics Control Module (VDCM) 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 VDCM is receiving the correct voltage. Use a multimeter to check the power supply to the module

  5. 5. Ground Connection

    Ensure that the ground connection for the VDCM is secure and functioning properly

  6. 6. Inspect the Vehicle Dynamics Control Module

    Module Condition: Check the VDCM for any physical damage or signs of failure

  7. 7. Reprogramming

    If applicable, consider reprogramming or updating the module’s software, as a software glitch can sometimes cause communication issues

  8. 8. Check for Communication Issues

    CAN Bus Communication: Since the VDCM communicates over the CAN bus, check for issues with the CAN bus wiring and other modules on the bus

  9. 9. Scan Other Modules

    Use a scan tool to check if other modules can communicate properly. If other modules are also having communication issues, it may indicate a problem with the CAN bus

  10. 10. Perform a Hard Reset

    Disconnect the vehicle's battery for a few minutes to reset the vehicle's computer systems. Reconnect and see if the code reappears

  11. 11. Test the VDCM

    If all else fails, you may need to test the VDCM itself. This may involve bench testing the module or replacing it with a known good unit to see if the problem persists

  12. 12. Consult Technical Service Bulletins (TSBs)

    Check for any TSBs related to the U1128 code or the specific vehicle make and model. Manufacturers may have issued guidance on common issues and fixes

  13. 13. Seek Professional Help

    If you are unable to resolve the issue after these steps, it may be best to consult a professional mechanic or technician who has experience with your specific vehicle make and model.Conclusion Troubleshooting OBD-II code U1128 involves a systematic approach to check for wiring issues, module functionality, and communication integrity. Always ensure safety precautions are taken when working on vehicle electronics