U2777 – Module Communication Failure

The ODBII code U2777 indicates a “Module Communication Failure,” meaning there is a problem with communication between vehicle control modules, which may affect their ability to exchange data properly.

The severity of ODBII code U2777 is moderate.

Common Causes For: U2776 Vehicle Communication Bus Malfunction

• Faulty wiring or connectors
• Malfunctioning control module
• Software issues or firmware bugs
• Power supply problems
• Grounding issues
• Corrupted data communication
• Interference from other electronic devices
• Poor or damaged CAN bus network

Common misdiagnosis for U2777 U2777: “Module Communication Failure”

• Faulty wiring or connectors
• Defective control modules
• Power supply issues
• Software glitches or outdated firmware
• Intermittent communication issues
• Grounding problems
• Incorrectly configured or programmed modules
• Faulty sensors or actuators

Common Troubleshooting Steps

The OBD-II code U2777 indicates a “Module Communication Failure,” which typically means that there is a problem with communication 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 other trouble codes that may be present. Sometimes, multiple codes can provide more context for the issue.
• Inspect Wiring and Connectors:
• Visually inspect the wiring and connectors associated with the affected 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 affected module is receiving the proper voltage and ground. Use a multimeter to check the power supply to the module.
• If the module is not receiving power, trace the wiring back to the fuse box and check for blown fuses or damaged wires.
• Test the Module:
• If possible, test the affected module by swapping it with a known good module (if applicable) to see if the problem persists.
• Some modules may have self-diagnostic capabilities; consult the service manual for specific testing procedures.
• Inspect the CAN Bus:
• The Controller Area Network (CAN) bus is responsible for communication between modules. Check for any issues with the CAN bus wiring, such as shorts or opens.
• Use an oscilloscope or a CAN bus diagnostic tool to monitor the bus for proper communication signals.
• 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 affected module.
• Clear Codes and Test Drive:
• After performing any repairs or inspections, 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 module communication.
• Professional Diagnosis:
• If the issue persists after performing the above steps, it may be necessary to seek the assistance of a professional mechanic or dealership with advanced diagnostic tools. By following these steps, you can systematically identify and resolve the underlying cause of the U2777 code.