U1335 – Module Communication Failure

The ODBII code U1335 indicates a communication failure between modules in the vehicle’s network, suggesting that one or more control modules are not able to communicate properly with each other.

The severity of ODBII code U1335: Module Communication Failure is moderate to severe.

Common Causes For: 1. U1329: Manufacturer Communication Error

• Faulty wiring or connectors
• Failed control module
• Poor ground connections
• Corroded or damaged connectors
• Communication network issues (e.g., CAN bus problems)
• Software or firmware issues in modules
• Low battery voltage or power supply issues
• Intermittent faults in the communication line

Common misdiagnosis for 1. U1335: Module Communication Failure

• Faulty wiring or connectors
• Defective control module
• Software issues or updates needed
• Power supply problems
• Grounding issues
• Intermittent communication issues
• Other module failures (e.g., ABS, BCM)
• Sensor malfunctions
• Corrupted data or configuration errors
• Environmental interference (e.g., electromagnetic interference)

Common Troubleshooting Steps

When dealing with OBD-II code U1335, which indicates a “Module Communication Failure,” it’s important to follow a systematic approach to troubleshoot the issue. Here are common troubleshooting steps:

• Check for Additional 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 ground connections, as poor grounding can lead to communication issues.
• Check Power Supply:
• Ensure that the module in question is receiving the proper voltage. Use a multimeter to check the power supply to the module.
• Verify that the fuses related to the module are intact.
• Test the Module:
• If possible, test the module itself. This may involve using a scan tool to communicate with the module and check for any internal faults.
• If the module is removable, consider swapping it with a known good module to see if the problem persists.
• Inspect the CAN Bus:
• U1335 often relates to issues with the Controller Area Network (CAN) bus. Check for any faults in the CAN bus wiring, such as shorts or opens.
• Use an oscilloscope or a CAN bus tester to monitor the bus for proper communication signals.
• Check for Interference:
• Look for any aftermarket devices or modifications that may interfere with the vehicle’s communication network. This includes alarms, stereo systems, or other electronic devices.
• Reset the Codes:
• After performing checks and repairs, clear the trouble codes using the OBD-II scanner and take the vehicle for a test drive to 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 issues related to module communication.
• Professional Diagnosis:
• If the issue persists after performing the above steps, consider seeking help from a professional mechanic or dealership. They may have specialized tools and knowledge to diagnose complex communication issues. By following these steps, you can systematically identify and resolve the underlying cause of the U1335 code.