U1302 – Module Communication Failure

The ODBII code U1302 indicates a “Module Communication Failure,” meaning there is a problem with communication between the vehicle’s control modules, often due to a wiring issue, a faulty module, or a network problem.

The severity of ODBII code U1302 is moderate.

Common Causes For: U1301 Class 2 Communication Bus Off.

• Faulty wiring or connectors
• Failed control module
• Corroded or damaged pins
• Poor ground connections
• Intermittent electrical issues
• Software glitches or incompatibility
• Low battery voltage or weak battery
• Faulty communication network (CAN bus issues)

Common misdiagnosis for U1302 U1302: “Module Communication Failure”

• Faulty wiring or connectors
• Defective control module
• Low battery voltage
• Corroded grounds
• Intermittent communication issues
• Software glitches or updates needed
• Faulty sensors
• Incorrectly installed aftermarket accessories

Common Troubleshooting Steps

The OBD-II code U1302 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 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 Module Power Supply:
• Ensure that the affected module(s) are receiving the proper voltage and ground. Use a multimeter to check the power supply to the module.
• If the module is not powered correctly, trace the wiring back to the power source.
• Test Communication Lines:
• Use a scan tool to check the communication lines (CAN bus, LIN bus, etc.) for continuity and proper voltage levels.
• If you have access to an oscilloscope, you can check the signal waveforms on the communication lines to ensure they are functioning correctly.
• Inspect for Short Circuits:
• Check for any short circuits in the wiring that could be causing interference with communication.
• Look for pinched or frayed wires that may be making contact with other circuits.
• Check for Module Malfunction:
• If the wiring and connections are good, the issue may be with the module itself. Consider testing or replacing the affected module.
• If you have access to a known good module, you can swap it in to see if the problem resolves.
• Reset the Modules:
• Sometimes, simply resetting the modules can clear communication errors. Disconnect the battery for a few minutes, then reconnect it and see if the code returns.
• Update Software/Firmware:
• Check if there are any software updates available for the vehicle’s control modules. Sometimes, communication issues can be resolved with a software update.
• Consult Wiring Diagrams:
• Refer to the vehicle’s service manual for wiring diagrams and communication protocols to better understand how the modules are supposed to communicate.
• Professional Diagnosis:
• If the issue persists after performing these steps, it may be necessary to consult a professional mechanic or technician who has experience with the specific vehicle make and model. By following these troubleshooting steps, you should be able to identify and resolve the underlying cause of the U1302 code.