U2728 – Vehicle Communication Bus Malfunction

The ODBII code U2728 indicates a malfunction in the vehicle communication bus, which affects the communication between various control modules in the vehicle.

The severity of ODBII code U2728 is generally considered moderate to severe.

Common Causes For: U2727 U2727: “Control Module Communication Failure”

• Faulty OBD-II connector
• Damaged wiring or connectors in the communication bus
• Malfunctioning control modules
• Poor ground connections
• Corroded or loose terminals
• Software issues or bugs in the control modules
• Interference from aftermarket devices
• Faulty or incompatible diagnostic tools
• Low battery voltage or power supply issues
• Faulty CAN bus transceiver

Common misdiagnosis for U2728 Vehicle Communication Bus Malfunction

• Faulty Engine Control Module (ECM)
• Defective Body Control Module (BCM)
• Bad wiring or connectors
• Malfunctioning sensors
• Issues with the powertrain control module (PCM)
• Battery or charging system problems
• Faulty diagnostic tools or software errors
• Incorrectly configured or incompatible aftermarket accessories

Common Troubleshooting Steps

The OBD-II code U2728 indicates a “Vehicle Communication Bus Malfunction.” This code typically points to issues with the communication between various control modules in the vehicle. 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 to the root cause of the problem.
• Inspect Wiring and Connectors:
• Visually inspect the wiring and connectors associated with the communication bus (CAN bus). Look for damaged, frayed, or corroded wires and loose connections.
• Pay special attention to the connectors on the ECM (Engine Control Module) and other control modules.
• Check for Short Circuits:
• Use a multimeter to check for short circuits in the communication lines. Ensure that the voltage levels are within the manufacturer’s specifications.
• Test the Communication Bus:
• Use a scan tool to monitor the communication between modules. Check if all modules are responding correctly.
• If certain modules are not communicating, it may indicate a problem with that specific module or its wiring.
• Inspect Modules:
• If a specific module is not communicating, inspect it for damage or failure. This may involve checking for water intrusion, physical damage, or internal faults.
• If possible, swap the suspected faulty module with a known good one to see if the issue resolves.
• Check Power and Ground:
• Ensure that all control modules have proper power and ground connections. A weak ground or insufficient power supply can cause communication issues.
• Look for Interference:
• Check for any aftermarket devices or modifications that may interfere with the communication bus. This includes alarm systems, stereo systems, or other electronic devices.
• Update Software/Firmware:
• Check if there are any software updates available for the vehicle’s control modules. Sometimes, updating the firmware can resolve communication issues.
• Clear Codes and Test Drive:
• After performing the above 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 Service Manual:
• Refer to the vehicle’s service manual for specific diagnostic procedures related to the U2728 code. This may provide additional insights or steps tailored to your vehicle model. 1
• Seek Professional Help:
• If the issue persists after performing these steps, it may be necessary to consult a professional mechanic or technician who has experience with vehicle communication systems. By following these troubleshooting steps, you can systematically identify and resolve the underlying issues causing the U2728 code.