U1860 – Communication Line Fault Detected

The ODBII code U1860: Communication Line Fault Detected indicates a problem with the communication network between various control modules in the vehicle, suggesting that one or more modules are unable to communicate properly.

The severity of ODBII code **U1860: Communication Line Fault Detected** is generally considered moderate to severe, as it indicates a communication issue within the vehicle’s network that can affect multiple systems.

Common Causes For: U1858: Module Communication Failure

• Faulty wiring or connectors in the communication line.
• Malfunctioning control modules.
• Poor ground connections.
• Short circuits in the communication circuit.
• Open circuits in the communication circuit.
• Interference from aftermarket devices.
• Corroded or damaged pins in connectors.

Common misdiagnosis for U1860: Communication Line Fault Detected

• Faulty Body Control Module (BCM)
• Defective wiring or connectors
• Malfunctioning Instrument Cluster
• Issues with the Powertrain Control Module (PCM)
• Faulty CAN bus communication
• Defective sensors or actuators
• Battery or charging system problems
• Grounding issues
• Software or firmware glitches
• Corrupted data in the vehicle’s computer systems

Common Troubleshooting Steps

The OBD-II code **U1860: Communication Line Fault Detected** indicates a problem with the communication network in the vehicle, specifically related to the Controller Area Network (CAN) bus. This code can be triggered by various issues, including wiring problems, module failures, or interference in the communication lines. Here are some common troubleshooting steps to diagnose and resolve the issue:

• 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 and help identify the faulty module.
• Inspect Wiring and Connectors: Visually inspect the wiring harnesses and connectors related to the CAN bus. Look for signs of damage, corrosion, loose connections, or frayed wires.
• Pay special attention to the connectors at the modules involved in the communication network.
• Test the CAN Bus: Use a multimeter or an oscilloscope to check the voltage levels on the CAN bus wires. The typical voltage levels should be around 2.5V to 3.5V when the vehicle is on.
• Check for short circuits or open circuits in the CAN bus wiring.
• Check for Module Functionality: Identify the modules that are part of the CAN network (e.g., Engine Control Module, Transmission Control Module, Body Control Module).
• Test each module for proper operation. If a specific module is not responding, it may need to be replaced or reprogrammed.
• Look for Interference: Check for any aftermarket devices or modifications that may interfere with the CAN bus communication. This includes alarms, stereo systems, or other electronic devices.
• Disconnect any non-factory devices and see if the code clears.
• Perform a Network Test: Some advanced scan tools can perform a network test to check the communication between modules. Use this feature to identify any modules that are not communicating properly.
• Check for Ground Issues: Ensure that all ground connections related to the CAN bus are secure and free of corrosion. Poor grounding can lead to communication issues.
• Clear Codes and Test Drive: After performing the above checks and repairs, clear the trouble codes using the OBD-II scanner.
• Take the vehicle for a test drive to see if the code reappears. Monitor the vehicle’s performance and any warning lights.
• Consult Service Manual: Refer to the vehicle’s service manual for specific diagnostic procedures related to the CAN bus and the U1860 code. This may provide additional insights or steps tailored to your vehicle model.
• 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 automotive electronics and CAN bus systems. By following these troubleshooting steps, you should be able to identify and resolve the underlying issue causing the U1860 code.