U2123 – Lost Communication with Vehicle Dynamics Control Module.

The ODBII 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.

The severity of ODBII code U2123 is generally considered moderate to high.

Common Causes For: U2122 U2122: Instrument Cluster Communication Failure

• 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 misdiagnosis for U2123 Lost Communication with Vehicle Dynamics Control Module.

• 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)

Common Troubleshooting Steps

The OBD-II code U2123 indicates a “Lost Communication with Vehicle Dynamics Control Module.” This code typically points to a communication issue between the Engine Control Module (ECM) and the Vehicle Dynamics Control Module (VDCM). 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: **Visual Inspection: Check the wiring harness and connectors related to the Vehicle Dynamics Control Module for any signs of damage, corrosion, or loose connections.
• **Connector Pins: Ensure that the pins in the connectors are not bent, corroded, or damaged.
• 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.
• Check the ground connections to ensure they are secure and free of corrosion.
• 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.
• If the module is suspected to be faulty, consider replacing it or testing it in another vehicle if available.
• 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.
• Use an oscilloscope or CAN bus diagnostic tool to monitor the communication signals on the bus.
• 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.
• 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.
• 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.
• 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.