U1769 – CAN Bus Communication Failure

The ODBII code U1769: CAN Bus Communication Failure indicates a problem with the communication between the vehicle’s control modules over the Controller Area Network (CAN) bus, which may affect the performance of various systems.

The severity of ODBII code U1769: CAN Bus Communication Failure is generally considered moderate to severe.

Common Causes For: U1768 U1768: Data Bus Communication Fault

• Faulty CAN bus wiring or connectors
• Malfunctioning CAN bus module
• Short circuit in the CAN bus
• Open circuit in the CAN bus
• Interference from other electronic devices
• Corroded or damaged connectors
• Faulty or incompatible aftermarket components
• Software or firmware issues in the control modules
• Low battery voltage or poor power supply
• Grounding issues in the vehicle’s electrical system

Common misdiagnosis for U1769 U1769: CAN Bus Communication Failure

• Faulty Engine Control Module (ECM)
• Defective Body Control Module (BCM)
• Bad wiring or connectors
• Faulty CAN Bus transceiver
• Malfunctioning sensors
• Power supply issues
• Grounding problems
• Software glitches or updates needed
• Faulty transmission control module (TCM)
• Issues with other communication modules

Common Troubleshooting Steps

The OBD-II code U1769 indicates a CAN (Controller Area Network) bus communication failure. This code typically points to issues with the communication between various modules in the vehicle. Here are some common troubleshooting steps to diagnose and resolve the U1769 code:

• Check for Other Codes: Use an OBD-II scanner to check for any additional trouble codes. Other codes may provide more context or indicate related issues.
• Inspect the CAN Bus Wiring: **Visual Inspection: Check the wiring and connectors associated with the CAN bus for any signs of damage, corrosion, or loose connections.
• **Continuity Test: Use a multimeter to test for continuity in the CAN bus wires. Look for breaks or shorts in the wiring.
• Check the Termination Resistors: Ensure that the CAN bus has the correct termination resistors (typically 120 ohms) at both ends of the bus. A missing or faulty resistor can cause communication issues.
• Inspect Modules: Check the modules connected to the CAN bus for proper operation. A malfunctioning module can disrupt communication.
• If possible, disconnect modules one at a time to see if the code clears or communication is restored.
• Test the CAN Bus Signal: Use an oscilloscope or a CAN bus analyzer to check the signal on the CAN bus. Look for proper voltage levels and signal integrity.
• The CAN High and CAN Low lines should show a differential voltage when the bus is active.
• Check for Interference: Look for sources of electrical interference that may affect the CAN bus communication, such as aftermarket accessories or modifications.
• Inspect Ground Connections: Ensure that all ground connections related to the CAN bus and modules are secure and free of corrosion.
• Battery and Power Supply Check: Verify that the vehicle’s battery is in good condition and that the electrical system is functioning properly. Low voltage can cause communication issues.
• Software Updates: Check if there are any available software updates for the vehicle’s modules. Sometimes, communication issues can be resolved with a software update.
• Clear Codes and Test Drive: After performing the above checks and repairs, clear the trouble codes and take the vehicle for a test drive to see if the code returns.1
• Professional Diagnosis: If the issue persists after performing these steps, consider seeking help from a professional mechanic or dealership with advanced diagnostic tools. By following these steps, you should be able to identify and resolve the underlying issue causing the U1769 code.