DTC U0139 - Lost Communication with Suspension Control Module B

Introduction

The DTC U0139 error code represents a communication problem between the engine control unit (ECU) and the suspension control module B. This error can occur in different vehicles and can affect not only the suspension performance but also the stability and safety of the vehicle. In this article, we will explore the symptoms, causes, diagnosis methods, and solutions to address this problem.

Symptoms

When DTC code U0139 occurs, the driver may notice several symptoms, including:

  • Warning light on the dashboard
  • Erratic suspension behavior (e.g. stiffness or excessive bump absorption)
  • Inability to adjust suspension (in case of active suspension)
  • Error messages on the vehicle display
  • Reduced stability while driving, especially when cornering

Cause

The causes of the DTC code U0139 can be many and include:

  • Damaged or loose cables :
    Compromised wiring can interrupt communication between the ECU and the suspension control module.
  • Suspension control module B malfunction :
    If the module itself has internal faults, it will not be able to communicate properly with the ECU.
  • Power problems :
    Insufficient or unstable voltage can affect the operation of the control unit and suspension module.
  • Electrical interference :
    Other electrical components or faults in the power system may cause interference in communication.
  • Connector corrosion :
    Oxidized or corroded connections can prevent proper signal transfer.

Diagnosis

Diagnosing DTC U0139 requires a systematic approach and the use of appropriate diagnostic tools. The basic steps include:

  1. DTC Code Scan :
    Use an OBD-II scanner to identify the U0139 code and other related codes such as U0140 (Lost Communication With Suspension Control Module A) and U0126 (Lost Communication With Stability Control Module).

  2. Visual inspection :
    Check the wires and connectors between the ECU and the suspension control module for any signs of damage or corrosion.

  3. Checking the voltage :
    Measure the supply voltage to the suspension control module to ensure it is within specified limits.

  4. Control Module Test :
    Use diagnostic tools to test the suspension control module for internal malfunctions.

  5. Signal Control :
    Monitor the control module input and output signals to check for communication abnormalities.

Resolution and repair

Once the problem is identified, the following strategies can be adopted to resolve the DTC U0139 code:

  • Cable Repair :
    If you find any damaged cables, they need to be repaired or replaced.

  • Replacing the control module :
    If the suspension control module B is found to be faulty, it may need to be replaced with a new or remanufactured one.

  • Cleaning the connectors :
    Clean the connectors with a specific product to remove corrosion and restore a good electrical connection.

  • Power Control :
    Make sure the power supply voltage is stable and within the specified range. If there are any power supply problems, they need to be solved.

  • System Reset :
    After making repairs, it is advisable to reset the system using an OBD-II scanner and check if the code recurs.

Insight: Components involved in the failure

It is helpful to understand the mechanical and electrical components involved in the DTC code U0139:

  • Suspension Control Module B :
    This component manages the active suspension functions, adjusting the stiffness and height of the vehicle based on road conditions and driver behavior.

  • Engine Control Unit (ECU) :
    It monitors and manages various vehicle systems, including the suspension. Communication between the ECU and the suspension module is crucial for the proper functioning of the system.

  • Wiring and connectors :
    These components are essential for the transfer of electrical signals. Any damage or wear can cause interruptions in communication.

Conclusions

DTC U0139 represents a significant issue in terms of vehicle safety and performance. Accurate diagnosis and timely repair are essential to ensure proper suspension operation and the safety of the driver and passengers. Always remember to follow standard diagnostic procedures and use appropriate tools to address this type of failure. With a good understanding of the causes and solutions, auto repairers can restore the vehicle to functionality effectively and safely.

Important
Not all OBD2 codes used by one manufacturer are used by other brands, and may not have the same meaning.
The information presented here is for informational purposes only. We are not responsible for any actions you take on your vehicle. If you have any concerns about repairing your vehicle, please contact your repair shop.