U1110 – Communication Bus Off.

The ODBII code U1110 indicates a communication issue where the vehicle’s control module is unable to communicate with other modules on the communication bus, often due to a fault in the network or a module failure.

The severity of ODBII code U1110 Communication Bus Off is moderate to severe.

Common Causes For: U1109 SCP (J1850) Invalid or Missing Data for Electric Traction Drive (Inverter)

• Faulty wiring or connectors in the communication bus.
• Malfunctioning control modules.
• Short circuits or open circuits in the bus lines.
• Corroded or damaged connectors.
• Interference from aftermarket devices.
• Software issues or bugs in the control modules.
• Low battery voltage or power supply issues.

Common misdiagnosis for U1110 Communication Bus Off.

• Faulty ABS module
• Defective engine control module (ECM)
• Bad wiring or connectors
• Malfunctioning body control module (BCM)
• Issues with the transmission control module (TCM)
• Faulty sensors
• Battery or charging system problems
• Incorrectly diagnosed communication issues with other modules

Common Troubleshooting Steps

The OBD-II code U1110 indicates a “Communication Bus Off” issue, which typically means that there is a problem with the communication between the vehicle’s control modules. This can be caused by various factors, including wiring issues, module failures, or problems with the communication bus itself. Here are some common troubleshooting steps to diagnose and resolve the U1110 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 communication bus (CAN bus, LIN bus, etc.). Look for signs of damage, corrosion, or loose connections.
• Pay special attention to the connectors on the modules that are part of the communication network.
• Test the Communication Bus: Use a multimeter or an oscilloscope to check the voltage levels and signal integrity on the communication bus wires.
• Ensure that the bus is receiving the correct voltage and that the signals are within the expected range.
• Check for Short Circuits or Open Circuits: Perform continuity tests to check for short circuits or open circuits in the communication lines.
• Disconnect modules one at a time to see if the code clears, which can help identify a faulty module.
• Inspect Modules: Check the control modules involved in the communication network for any signs of failure or damage.
• If a specific module is suspected to be faulty, consider replacing or reprogramming it.
• Check for Ground Issues: Ensure that all ground connections related to the communication bus are secure and free of corrosion.
• A poor ground can lead to communication issues.
• Look for Interference: Check for any aftermarket devices or modifications that may interfere with the communication bus.
• Remove or disconnect any non-factory equipment to see if the issue resolves.
• Perform a Network Scan: Use a professional-grade scan tool to perform a network scan. This can help identify which module is not communicating properly.
• Clear Codes and Test Drive: After performing the above checks and repairs, clear the trouble codes and take the vehicle for a test drive to see if the code returns.
• Consult Service Manual: Refer to the vehicle’s service manual for specific diagnostic procedures related to the communication bus and the U1110 code.1
• Seek Professional Help: If the issue persists after performing these steps, consider seeking help from a qualified technician or automotive professional who has experience with OBD-II systems. By following these troubleshooting steps, you should be able to identify and resolve the underlying issue causing the U1110 code.