U1387 – Control Module Communication Failure

The ODBII code U1387 indicates a communication failure between control modules in a vehicle, suggesting that one or more modules are not properly communicating with each other.

The severity of ODBII code U1387 is moderate.

Common Causes For: U1386 Invalid Data Received from Vehicle Control Module.

• Faulty control module
• Poor electrical connections
• Damaged wiring harness
• Corroded connectors
• Software issues or bugs
• Low battery voltage
• Interference from aftermarket devices
• Faulty CAN bus communication
• Grounding issues

Common misdiagnosis for U1387 U1387: “Control Module Communication Failure”

• Faulty control module
• Wiring issues
• Poor ground connections
• Corrupted software or firmware
• Faulty sensors
• Battery or power supply problems
• Intermittent connection issues
• Communication network faults (e.g., CAN bus issues)

Common Troubleshooting Steps

The OBD-II code U1387 indicates a “Control Module Communication Failure.” This code typically suggests that there is a problem with communication between the vehicle’s control modules. Here are some common troubleshooting steps to diagnose and resolve this issue:

• Check for Other Codes: Use an OBD-II scanner to check for any other trouble codes that may be present. Sometimes, multiple codes can provide more context for the issue.
• Inspect Wiring and Connectors:
• Visually inspect the wiring and connectors associated with the control modules. Look for signs of damage, corrosion, or loose connections.
• Pay special attention to the wiring harnesses that connect the affected control modules.
• Check Power and Ground:
• Ensure that the control modules have proper power and ground connections. Use a multimeter to check for voltage and continuity.
• If there is no power or ground, trace the wiring back to the source to identify any breaks or shorts.
• Test Control Modules:
• If possible, test the affected control modules to ensure they are functioning correctly. This may involve using specialized diagnostic tools or swapping with known good modules.
• Check for any software updates or reprogramming that may be required for the control modules.
• Inspect the CAN Bus:
• The communication between control modules often occurs over a Controller Area Network (CAN) bus. Inspect the CAN bus wiring for damage or shorts.
• Use a scan tool to monitor the CAN bus for any irregularities in communication.
• Check for Interference:
• Look for any aftermarket devices or modifications that may interfere with the communication between control modules. This includes alarms, stereo systems, or other electronic devices.
• 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 U1387 code. This may provide additional insights or steps tailored to your vehicle’s make and 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 your vehicle’s specific systems. By following these troubleshooting steps, you can systematically identify and resolve the underlying issue causing the U1387 code.