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U code network High severity

U1139 Lost Communication with Vehicle Dynamics Control Module

The OBD2 code U1139 indicates a loss of communication with the Vehicle Dynamics Control Module, which may affect the vehicle's stability and traction control systems

Definition

The OBD2 code U1139 indicates a loss of communication with the Vehicle Dynamics Control Module, which may affect the vehicle's stability and traction control systems

Common causes

  • Faulty Vehicle Dynamics Control Module (VDCM)
  • Damaged or corroded wiring or connectors
  • Poor ground connection
  • Faulty communication network (CAN bus issues)
  • Malfunctioning sensors related to vehicle dynamics
  • Software or firmware issues in the VDCM
  • Battery or power supply issues affecting the VDCM
  • Intermittent electrical connections

Common misdiagnoses

  • Faulty ABS module
  • Defective wheel speed sensors
  • Malfunctioning engine control module (ECM)
  • Wiring issues or shorts in the communication lines
  • Faulty powertrain control module (PCM)
  • Incorrectly diagnosed brake system issues
  • Battery or charging system problems
  • Faulty or corroded connectors
  • Issues with the traction control system
  • Misinterpretation of other related codes

Troubleshooting steps

  1. 1. Check for Other Codes

    Use an OBD-II scanner to check for any additional trouble codes. Sometimes, multiple codes can provide more context about the issue

  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 any issues with the CAN network. Look for other modules that may not be communicating properly

  9. 9. Bus Termination

    Ensure that the CAN bus is properly terminated. A missing or faulty termination resistor can lead to communication problems

  10. 10. Test the VDCM

    If possible, perform a functional test of the VDCM using a scan tool that can communicate with the module. This can help determine if the module is operational

  11. 11. Inspect Related Systems

    Check other systems that may interact with the VDCM, such as the ABS, traction control, or stability control systems. Issues in these systems can sometimes affect communication

  12. 12. 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

  13. 13. 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 VDCM

  14. 14. Seek Professional Help

    If the issue persists after performing these 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 can systematically identify and address the cause of the U1139 code