U1366 – Control Module Communication Failure

The ODBII code U1366 indicates a “Control Module Communication Failure,” meaning there is a problem with communication between the vehicle’s control modules, which can affect various systems and functions.

The severity of ODBII code U1366 is moderate.

Common Causes For: U1365 U1365: “Control Module Communication Failure”

• 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 U1366 U1366: “Control Module Communication Failure”

• Faulty control module
• Wiring issues
• Poor ground connections
• Corrupted software/firmware
• Faulty sensors
• Battery or charging system problems
• Intermittent connection issues
• Communication network faults (CAN bus issues)

Common Troubleshooting Steps

The OBD-II code U1366 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 additional trouble codes. Sometimes, other codes can provide context or lead you to the root cause of the communication failure.
• 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 ground connections, as poor grounding can lead to communication issues.
• Check for Short Circuits:
• Use a multimeter to check for short circuits in the wiring harnesses. A short can disrupt communication between modules.
• Verify Power Supply:
• Ensure that the control modules are receiving the proper voltage. Check the power supply to the affected module(s) and ensure that the battery is in good condition.
• Inspect Control Modules:
• If possible, check the affected control module for any signs of damage or failure. This may involve removing the module and inspecting it for physical damage.
• Perform a Network Test:
• Some advanced scan tools can perform a network test to check the communication between modules. This can help identify which module is not communicating properly.
• Check for Software Updates:
• Sometimes, a software update for the control modules can resolve communication issues. Check with the manufacturer for any available updates.
• Reset the System:
• Clear the trouble codes using the OBD-II scanner and see if the code returns. Sometimes, a temporary glitch can cause communication failures.
• Consult Wiring Diagrams:
• Refer to the vehicle’s wiring diagrams to understand the communication network and identify any potential issues in the communication lines.
• Professional Diagnosis:
• If the issue persists after performing the above steps, it may be necessary to consult a professional mechanic or technician who has experience with the specific vehicle make and model. They may have access to specialized diagnostic tools and equipment. By following these steps, you can systematically diagnose and potentially resolve the U1366 code. Always refer to the vehicle’s service manual for specific procedures and specifications related to your vehicle.