U2900 – Lost Communication with Vehicle Control Module.

The ODBII code U2900 indicates a loss of communication with the vehicle control module, suggesting that the module is not responding or is unable to communicate with other systems in the vehicle.

The severity of ODBII code U2900 is generally considered moderate to high.

Common Causes For: U2899 Lost Communication with the Steering Angle Sensor.

• Faulty wiring or connectors
• Failed Vehicle Control Module (VCM)
• Corroded or damaged connectors
• Poor ground connections
• Intermittent electrical issues
• Software or firmware issues
• Faulty communication network (CAN bus issues)
• Other module failures affecting communication

Common misdiagnosis for U2900 Lost Communication with Vehicle Control Module.

• Faulty Vehicle Control Module (VCM)
• Wiring issues or damaged connectors
• Faulty or corroded ground connections
• Issues with the power supply to the VCM
• Problems with other communication modules
• Faulty diagnostic tools or software
• Incorrectly configured or programmed modules
• Battery or charging system issues

Common Troubleshooting Steps

The OBD-II code U2900 indicates a “Lost Communication with Vehicle Control Module.” This code typically suggests that there is a communication issue between the vehicle’s control modules. Here are some common troubleshooting steps to diagnose and resolve this issue:

• 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.
• Inspect Wiring and Connectors:
• Visually inspect the wiring and connectors associated with the affected control module. Look for signs of damage, corrosion, or loose connections.
• Pay special attention to the ground connections, as poor grounding can lead to communication issues.
• Check Power Supply:
• Ensure that the control module is receiving the proper voltage. Use a multimeter to check the power supply to the module.
• Verify that the fuses related to the control module are intact and functioning.
• Test the Control Module:
• If possible, test the control module itself. This may involve using specialized diagnostic tools or swapping the module with a known good one to see if the problem persists.
• Inspect the CAN Bus:
• The communication between control modules often occurs over the Controller Area Network (CAN) bus. Check for any issues with the CAN bus wiring, such as shorts or opens.
• Use a CAN bus scanner to monitor the communication and identify any anomalies.
• Check for Interference:
• Look for any aftermarket devices or modifications that may interfere with the vehicle’s communication systems. This includes alarm systems, stereo installations, or other electronic devices.
• Reset the Codes:
• After performing inspections and repairs, clear the trouble codes using an OBD-II scanner and take the vehicle for a test drive to see if the code returns.
• Consult Technical Service Bulletins (TSBs):
• Check for any manufacturer-specific TSBs related to the U2900 code or communication issues. There may be known fixes or updates available.
• Professional Diagnosis:
• If the issue persists after performing the above steps, consider seeking help from a professional mechanic or dealership. They may have access to advanced diagnostic tools and resources. By following these steps, you can systematically identify and resolve the communication issue associated with the U2900 code.