U1887 – Module Communication Line Fault

The ODBII code U1887 indicates a communication fault between modules in a vehicle, suggesting that one or more control modules are unable to communicate properly with each other.

The severity of ODBII code U1887 is generally considered moderate.

Common Causes For: U1885 U1885: “Data Bus Communication Failure”

• Faulty wiring or connectors
• Corroded or damaged connectors
• Short circuits in the communication line
• Open circuits in the communication line
• Malfunctioning control modules
• Software issues or incompatibility between modules
• Poor ground connections
• Interference from aftermarket devices or modifications

Common misdiagnosis for U1887 U1887: “Module Communication Line Fault”

• Faulty wiring or connectors
• Defective control modules
• Software issues or updates needed
• Battery or power supply problems
• Grounding issues
• Intermittent communication faults
• Other communication line faults (e.g., CAN bus issues)

Common Troubleshooting Steps

The OBD-II code U1887 indicates a “Module Communication Line Fault.” This code typically suggests that there is a communication issue between the vehicle’s control modules. Here are some common troubleshooting steps to diagnose and resolve the issue:

• Check for Other Codes: Start by scanning the vehicle for any other diagnostic trouble codes (DTCs). Other codes may provide additional context or indicate which module is having communication issues.
• Inspect Wiring and Connectors:
• Visually inspect the wiring and connectors associated with the affected modules. Look for signs of damage, corrosion, or loose connections.
• Pay special attention to the communication lines (CAN bus lines) for any signs of wear or damage.
• Check Power and Ground:
• Ensure that the affected modules have proper power and ground connections. Use a multimeter to check voltage and ground continuity.
• If a module is not receiving power or ground, trace the circuit back to find the issue.
• Test Communication Lines:
• Use a scan tool to monitor the communication between modules. Check if the affected module is responding to requests from other modules.
• If possible, use an oscilloscope to check the signal integrity on the CAN bus lines.
• Inspect Modules:
• If a specific module is identified as the source of the problem, inspect it for physical damage or signs of failure.
• If necessary, perform a reset or reprogram the module according to the manufacturer’s specifications.
• Check for Intermittent Issues:
• Sometimes, communication faults can be intermittent. Pay attention to the conditions under which the fault occurs (e.g., temperature, vibration, etc.).
• If the issue is intermittent, it may be helpful to monitor the vehicle’s performance over time.
• Update Software/Firmware:
• Check if there are any software or firmware updates available for the vehicle’s modules. Sometimes, communication issues can be resolved with an update.
• Consult Wiring Diagrams:
• Refer to the vehicle’s service manual for wiring diagrams and communication protocols. This can help you understand how the modules are interconnected.
• Perform a Network Test:
• Some advanced scan tools can perform a network test to identify communication issues between modules. This can help pinpoint the problem.
• Seek Professional Help:
• If the issue persists after performing these steps, it may be necessary to consult a professional technician or dealership with experience in diagnosing complex communication issues. By following these steps, you should be able to identify and resolve the underlying cause of the U1887 code.