U2935 – Vehicle Communication Bus Malfunction

The ODBII code U2935 indicates a malfunction in the vehicle communication bus, which affects the ability of various electronic control units (ECUs) to communicate with each other.

The severity of ODBII code U2935 is moderate.

Common Causes For: U2934 U2934: “Vehicle Communication Bus Malfunction”

• Faulty wiring or connectors in the communication bus
• Malfunctioning control modules
• Corrupted software or firmware in control modules
• Poor ground connections
• Short circuits or open circuits in the communication lines
• Interference from aftermarket devices
• Damaged or defective OBD-II port
• Low battery voltage or power supply issues

Common misdiagnosis for U2935 U2935: “Vehicle Communication Bus Malfunction”

• Faulty OBDII connector
• Bad ground connections
• Defective ECM (Engine Control Module)
• Malfunctioning BCM (Body Control Module)
• Wiring issues or shorts in the communication lines
• Faulty sensors or actuators
• Software glitches or outdated firmware
• Issues with the CAN bus system
• Corrupted data from diagnostic tools
• Interference from aftermarket accessories

Common Troubleshooting Steps

When dealing with OBD-II code U2935, which indicates a “Vehicle Communication Bus Malfunction,” there are several common troubleshooting steps you can follow to diagnose and potentially resolve the issue. Here’s a structured approach:

• 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 the Wiring and Connectors: **Visual Inspection: Look for any damaged, frayed, or corroded wiring and connectors related to the communication bus (CAN bus).
• **Connector Integrity: Ensure that all connectors are securely attached and free of corrosion or dirt.
• Check the Battery and Ground Connections: Ensure that the vehicle’s battery is in good condition and fully charged.
• Check the ground connections for the modules involved in the communication bus. Poor ground connections can lead to communication issues.
• Test the Communication Bus: Use a multimeter or an oscilloscope to check the voltage levels on the CAN bus wires. The typical voltage should be around 2.5V when idle.
• Look for any short circuits or open circuits in the communication lines.
• Inspect Modules: Identify the modules that are part of the communication bus (e.g., Engine Control Module, Transmission Control Module, Body Control Module).
• Check for any signs of failure or malfunction in these modules. If possible, perform a module reset or reprogramming.
• Check for Interference: Look for any aftermarket devices or modifications that may interfere with the vehicle’s communication systems (e.g., alarms, stereo systems, etc.).
• Perform a Network Test: If available, use a professional scan tool to perform a network test. This can help identify which module is not communicating properly.
• Clear Codes and Test Drive: After performing the above checks and repairs, clear the trouble codes using the OBD-II scanner.
• 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 your vehicle. Manufacturers may have issued guidance on common issues related to the communication bus.
• 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 your vehicle’s specific systems. By following these steps, you should be able to identify and potentially resolve the issue related to the U2935 code.