U1965 – Data Bus Communication Failure.

The ODBII code U1965 indicates a communication failure on the data bus, meaning that there is a problem with the communication between various control modules in the vehicle.

The severity of ODBII code U1965 is moderate.

Common Causes For: U1962 Lost Communication with the Hybrid Powertrain Control Module (HPCM) 2.

• Faulty wiring or connectors in the data bus system.
• Malfunctioning control modules.
• Poor ground connections.
• Interference from aftermarket devices.
• Corroded or damaged pins in connectors.
• Software issues or bugs in the control modules.
• Low battery voltage or power supply issues.

Common misdiagnosis for U1965 Data Bus Communication Failure.

• Faulty ECM (Engine Control Module)
• Bad wiring or connectors
• Defective sensors
• Malfunctioning body control module (BCM)
• Issues with the instrument cluster
• Power supply problems
• Software glitches or updates needed
• Faulty communication lines or networks
• Incorrectly installed aftermarket accessories
• Grounding issues

Common Troubleshooting Steps

The OBD-II code U1965 indicates a “Data Bus Communication Failure.” This code typically points to issues with the communication between various modules in the vehicle’s network. 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 you to the root cause of the communication failure.
• Inspect Wiring and Connectors:
• Visually inspect the wiring harnesses and connectors associated with the modules on the data bus. Look for signs of damage, corrosion, or loose connections.
• Pay special attention to the connectors for the modules that are involved in the communication.
• Check the Modules:
• Identify which modules are part of the data bus and check their functionality. This may include the Engine Control Module (ECM), Transmission Control Module (TCM), Body Control Module (BCM), and others.
• If possible, perform a module reset or reprogramming if you suspect a software issue.
• Test the Data Bus:
• Use a multimeter or an oscilloscope to test the data bus for proper voltage levels and signal integrity. Look for short circuits or open circuits in the data lines.
• Check for proper termination resistors if applicable.
• Check for Ground Issues: Ensure that all modules have a good ground connection. Poor grounding can lead to communication failures.
• Inspect for Interference: Look for any aftermarket devices or modifications that may interfere with the data bus communication, such as alarms, stereo systems, or other electronic accessories.
• Perform a Network Scan: If you have access to advanced diagnostic tools, perform a network scan to see which modules are communicating and which are not. This can help pinpoint the problematic module.
• Clear Codes and Test Drive: After performing any repairs or adjustments, clear the trouble codes and take the vehicle for a test drive to see if the code reappears.
• Consult Technical Service Bulletins (TSBs): Check for any TSBs related to your vehicle make and model that may address known issues with data bus communication.
• Seek Professional Help: If the issue persists after performing these steps, it may be necessary to consult a professional mechanic or technician who specializes in automotive electronics. By following these steps, you should be able to identify and resolve the underlying issue causing the U1965 code.