U2755 – Control Module Communication Bus Off.

The ODBII code U2755 indicates a communication issue where a control module is unable to communicate on the vehicle’s communication bus, often due to a fault in the module or wiring.

The severity of ODBII code U2755 is moderate to severe.

Common Causes For: U2754 Invalid Data Received from the Transmission Control Module (TCM)”.

• Faulty control module
• Poor electrical connections or wiring issues
• Short circuits in the communication bus
• Corroded connectors
• Faulty or damaged communication bus wiring
• Software or firmware issues in the control module
• Interference from aftermarket devices
• Low battery voltage or power supply issues

Common misdiagnosis for U2755 Control Module Communication Bus Off.

• Faulty control module
• Wiring issues
• Poor ground connections
• Corroded connectors
• Faulty communication bus
• Battery or power supply problems
• Software issues or updates needed
• Other unrelated sensor failures

Common Troubleshooting Steps

The OBD-II code U2755 indicates a communication issue on the control module communication bus, specifically that a module is “off” or not responding. This can be caused by various issues, including wiring problems, module failures, or issues with the communication bus itself. Here are some common troubleshooting steps to diagnose and resolve the U2755 code:

• Check for Additional Codes: Use an OBD-II scanner to check for any other trouble codes that may be present. This can provide more context about the issue.
• Inspect Wiring and Connectors: Visually inspect the wiring and connectors related to the control modules on the communication bus. 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 the Control Modules: Identify the control module that is reporting the U2755 code. This may require consulting the vehicle’s service manual.
• If possible, test the control module for proper operation. This may involve checking for power and ground at the module and ensuring it is functioning correctly.
• Test the Communication Bus: Use a multimeter or an oscilloscope to check the communication signals on the bus. Look for proper voltage levels and signal integrity.
• If you have access to a scan tool that can monitor live data, check for communication between modules.
• Check for Short Circuits or Open Circuits: Use a multimeter to check for short circuits or open circuits in the communication lines. This may involve checking resistance and continuity in the wiring.
• Inspect for Interference: Look for any aftermarket devices or modifications that may be interfering with the communication bus. This includes alarms, stereo systems, or other electronic devices.
• Reset the Control Modules: Sometimes, simply resetting the control modules can resolve communication issues. This can be done by disconnecting the battery for a few minutes or using a scan tool to clear the codes.
• Update or Reprogram Modules: If the control module is not responding due to software issues, check if there are any available updates or reprogramming procedures from the manufacturer.
• Replace Faulty Components: If a specific control module is determined to be faulty after testing, it may need to be replaced. Ensure that any replacement module is compatible with the vehicle.
• Consult Technical Service Bulletins (TSBs): Check for any TSBs related to the U2755 code for your specific vehicle make and model. Manufacturers may have issued guidance on common issues and fixes.1
• Seek Professional Help: If the issue persists after performing these steps, it may be necessary to consult a professional mechanic or technician who has experience with OBD-II systems and can perform more advanced diagnostics. By following these troubleshooting steps, you should be able to identify and resolve the underlying issue causing the U2755 code.