U2277 – Control Module Communication Bus Fault

The ODBII code U2277: Control Module Communication Bus Fault indicates a problem with the communication between control modules in a vehicle, suggesting that one or more modules are not able to communicate properly over the vehicle’s data bus.

The severity of ODBII code U2277 is generally considered moderate to severe.

Common Causes For: U2274 Control Module Communication Bus Off.

• Faulty control module
• Damaged wiring or connectors
• Poor ground connections
• Corroded terminals
• Intermittent electrical connections
• Software issues or bugs
• Faulty communication bus (CAN bus) components
• Short circuits in the communication lines
• Open circuits in the communication lines
• Incompatible or malfunctioning aftermarket devices

Common misdiagnosis for U2277 U2277: Control Module Communication Bus Fault

• Faulty control module
• Wiring issues
• Poor ground connections
• Corrupted software/firmware
• Faulty sensors
• Battery or power supply issues
• Intermittent connection problems
• Incorrectly installed aftermarket components

Common Troubleshooting Steps

The OBD-II code U2277 indicates a “Control Module Communication Bus Fault.” This code typically points to a problem with the communication between various control modules in the vehicle. Here are some common troubleshooting steps to diagnose and resolve this issue:

• Check for Additional Codes: Use an OBD-II scanner to check for any other trouble codes that may be present. Other codes can provide context and help identify the root cause of the communication issue.
• Inspect Wiring and Connectors: Visually inspect the wiring and connectors associated with the control modules. Look for signs of damage, corrosion, loose connections, or frayed wires.
• Pay special attention to the connectors for the modules involved in the communication bus.
• Check the Control Modules: Ensure that all control modules are functioning properly. If a specific module is malfunctioning, it may disrupt communication on the bus.
• If possible, test the modules individually to confirm they are operational.
• Test the Communication Bus: Use a multimeter or an oscilloscope to check the communication bus (CAN bus, LIN bus, etc.) for proper voltage levels and signals.
• Look for short circuits, open circuits, or any abnormal signals on the bus.
• Inspect for Ground Issues: Ensure that all control modules have a good ground connection. Poor grounding can lead to communication issues.
• Check the ground points for corrosion or loose connections.
• Check for Interference: Look for any aftermarket devices or modifications that may interfere with the communication bus. This includes alarms, stereo systems, or other electronic devices.
• Update or Reprogram Modules: In some cases, a software update or reprogramming of the control modules may be necessary. Check with the manufacturer for any available updates.
• Clear Codes and Test Drive: After performing any repairs or adjustments, 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): Check for any TSBs related to the specific make and model of the vehicle. Manufacturers may have issued guidance on common issues related to communication faults.
• 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 automotive electronics and communication systems. By following these troubleshooting steps, you can systematically identify and resolve the underlying cause of the U2277 code.