U1936 – Module Communication Failure

The ODBII code U1936 indicates a communication failure between modules in a vehicle’s network, suggesting that one or more control modules are not able to communicate properly with each other.

The severity of ODBII code U1936 is generally considered moderate.

Common Causes For: U1935 CAN Communication Bus Fault.

• Faulty wiring or connectors
• Failed or malfunctioning control module
• Corrupted software or firmware in the module
• Poor ground connections
• Interference from aftermarket devices
• Low battery voltage or power supply issues
• Communication network issues (e.g., CAN bus problems)
• Damaged or corroded pins in connectors

Common misdiagnosis for U1936 U1936: “Module Communication Failure”

• Faulty wiring or connectors
• Defective control module
• Software issues or updates needed
• Battery or power supply problems
• Grounding issues
• Intermittent communication issues
• Other communication protocol failures

Common Troubleshooting Steps

The OBD-II code U1936 indicates a “Module Communication Failure,” which typically means 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 affected module. 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 Power Supply:
• Ensure that the affected module is receiving the proper voltage and ground. Use a multimeter to check the power supply to the module.
• If the module is not receiving power, trace the wiring back to the fuse box and check for blown fuses or damaged wires.
• Test the Module:
• If possible, test the affected module to ensure it is functioning correctly. This may involve swapping it with a known good module or using specialized diagnostic equipment.
• If the module is faulty, it may need to be repaired or replaced.
• Check for Communication:
• Use a scan tool to check if the affected module is communicating with other modules. If it is not, there may be a communication bus issue.
• Verify that the communication protocols (e.g., CAN, LIN) are functioning correctly.
• Inspect the CAN Bus:
• If the vehicle uses a CAN bus system, check for any short circuits or open circuits in the CAN wiring.
• Use an oscilloscope or a CAN bus analyzer to monitor the data lines for proper signal levels and activity.
• Look for Interference:
• Check for any aftermarket devices or modifications that may interfere with the vehicle’s communication systems.
• Remove or disconnect any non-factory equipment to see if the issue resolves.
• Reset the Modules:
• Sometimes, resetting the modules can clear communication errors. Disconnect the battery for a few minutes, then reconnect it and see if the code returns.
• Consult Technical Service Bulletins (TSBs):
• Check for any TSBs related to the specific make and model of the vehicle. Manufacturers may have issued guidance on common communication issues.
• Professional Diagnosis:
• If the issue persists after performing these steps, consider seeking help from a professional mechanic or dealership with experience in diagnosing communication issues. By following these steps, you should be able to identify and resolve the underlying cause of the U1936 code.