U2697 – Vehicle Communication Bus Malfunction

The ODBII code U2697 indicates a malfunction in the vehicle communication bus, which affects the communication between various control modules in the vehicle.

The severity of ODBII code U2697 is moderate.

Common Causes For: U2696 Invalid Data Received from Vehicle Dynamics Control Module.

• Faulty OBD-II connector
• Damaged wiring or connectors in the communication bus
• Malfunctioning ECU (Electronic Control Unit)
• Software issues or bugs in the vehicle’s control modules
• Poor ground connections
• Interference from aftermarket devices
• Corroded or loose pins in the connectors
• Faulty or incompatible diagnostic tool
• Issues with the vehicle’s battery or power supply
• Faulty communication modules (e.g., CAN bus, LIN bus)

Common misdiagnosis for U2697 Vehicle Communication Bus Malfunction

• Faulty Engine Control Module (ECM)
• Defective Body Control Module (BCM)
• Bad wiring or connectors
• Malfunctioning sensors
• Issues with the powertrain control module (PCM)
• Battery or charging system problems
• Incorrectly diagnosed transmission issues
• Faulty diagnostic tools or software errors

Common Troubleshooting Steps

The OBD-II code U2697 indicates a “Vehicle Communication Bus Malfunction.” This code typically points to issues with the communication between various modules in the vehicle, often related to the Controller Area Network (CAN) bus. 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. Sometimes, other codes can provide context or indicate which module is having issues.
• Inspect Wiring and Connectors:
• Visually inspect the wiring and connectors associated with the CAN bus. Look for signs of damage, corrosion, or loose connections.
• Pay special attention to the connectors at the Engine Control Module (ECM), Transmission Control Module (TCM), and any other modules that communicate over the bus.
• Check for Short Circuits:
• Use a multimeter to check for short circuits in the CAN bus wiring. Ensure that the wires are not shorted to ground or to each other.
• Test the Modules:
• If you suspect a specific module is causing the issue, you can test it by disconnecting it and checking if the code persists. If the code goes away, the module may be faulty.
• Reconnect the module and check for proper operation.
• Inspect the CAN Bus Termination:
• Ensure that the CAN bus has proper termination resistors (typically 120 ohms) at both ends of the bus. A missing or faulty resistor can cause communication issues.
• Check for Interference:
• Look for any aftermarket devices or modifications that may interfere with the CAN bus communication, such as alarms, remote starters, or stereo systems.
• Scan for Communication Issues:
• Use a professional-grade scan tool to monitor the communication between modules. This can help identify if a specific module is not responding or if there are communication errors.
• Update Software/Firmware:
• Check if there are any software or firmware updates available for the vehicle’s modules. Sometimes, manufacturers release updates to fix communication issues.
• Battery and Ground Connections:
• Ensure that the vehicle’s battery is in good condition and that all ground connections are clean and secure. Poor power supply or grounding can lead to communication problems.
• Consult Technical Service Bulletins (TSBs):
• Check for any TSBs related to the specific make and model of the vehicle. Manufacturers may have documented known issues and solutions for communication problems. 1
• Professional Diagnosis:
• If the issue persists after performing these steps, consider seeking help from a professional mechanic or dealership. They may have specialized tools and knowledge to diagnose complex communication issues. By following these steps, you can systematically identify and resolve the underlying cause of the U2697 code.