U1933 – Module Communication Fault

The ODBII code U1933: Module Communication Fault indicates a communication issue between vehicle modules, suggesting that one or more modules are not properly exchanging data.

The severity of ODBII code **U1933: Module Communication Fault** is generally considered moderate.

Common Causes For: U1932: Module Communication Failure

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

Common misdiagnosis for U1933: Module Communication Fault

• Faulty wiring or connectors
• Defective control module
• Software issues or firmware corruption
• Power supply problems
• Grounding issues
• Intermittent communication faults
• Incorrectly configured or programmed modules
• Other communication protocol errors

Common Troubleshooting Steps

The OBD-II code **U1933: Module Communication Fault** indicates a communication issue between modules in the vehicle’s network. This can be caused by various factors, including wiring issues, faulty modules, or problems with the vehicle’s communication protocols. Here are some common troubleshooting steps to diagnose and resolve the issue:

• Check for Other Codes:
• Use an OBD-II scanner to check for any additional trouble codes. Other codes may provide more context or indicate which module is having communication issues.
• Inspect Wiring and Connectors:
• Visually inspect the wiring harnesses and connectors associated with the affected modules. Look for signs of damage, corrosion, loose connections, or broken wires.
• Pay special attention to ground connections, as poor grounding can lead to communication faults.
• Check Module Power Supply:
• Ensure that the affected modules are receiving the correct voltage and ground. Use a multimeter to check for proper voltage at the module connectors.
• Test Communication Lines:
• Use a scan tool to check the communication lines (CAN bus, LIN bus, etc.) for proper operation. You can use an oscilloscope to monitor the signal patterns on the communication lines.
• Look for any interruptions or irregularities in the communication signals.
• Inspect for Water Intrusion:
• Check for signs of water intrusion in the module areas, as moisture can cause communication issues. Look for rust or corrosion on connectors and modules.
• Perform a Module Reset:
• Sometimes, resetting the affected modules can resolve communication issues. Disconnect the battery for a few minutes or use a scan tool to clear the codes and reset the modules.
• Check for Software Updates:
• Verify if there are any software updates available for the vehicle’s modules. Sometimes, manufacturers release updates to fix communication issues.
• Replace Faulty Modules:
• If a specific module is identified as faulty (e.g., through testing or if it is not responding), consider replacing it. Ensure that the replacement module is compatible with your vehicle.
• Consult Wiring Diagrams:
• Refer to the vehicle’s service manual for wiring diagrams and communication protocols. This can help you trace the communication lines and identify potential issues.
• Seek Professional Help:
• If the issue persists after performing the above steps, it may be necessary to consult a professional technician or a dealership with advanced diagnostic tools to further investigate the problem. By following these troubleshooting steps, you can systematically identify and resolve the underlying cause of the U1933 code.