U1705 – CAN Communication Bus Fault.

The ODBII code U1705 indicates a fault in the CAN (Controller Area Network) communication bus, suggesting a problem with data transmission between modules in the vehicle’s network.

The severity of ODBII code U1705 CAN Communication Bus Fault is generally considered moderate to severe.

Common Causes For: U1704 CAN Communication Bus Fault.

• Faulty CAN bus wiring or connectors
• Defective CAN bus module
• Short circuit in the CAN bus
• Open circuit in the CAN bus
• Interference from other electrical components
• Poor ground connections
• Faulty or incompatible aftermarket accessories
• Software issues or bugs in the vehicle’s control modules

Common misdiagnosis for U1705 CAN Communication Bus Fault.

• Faulty Engine Control Module (ECM)
• Faulty Transmission Control Module (TCM)
• Bad wiring or connectors
• Faulty Body Control Module (BCM)
• Defective sensors
• Battery or charging system issues
• Faulty CAN bus transceiver
• Software issues or updates needed
• Grounding issues
• Intermittent electrical connections

Common Troubleshooting Steps

The OBD-II code U1705 indicates a CAN (Controller Area Network) communication bus fault. This code typically suggests that there is a problem with the communication between various modules in the vehicle. Here are some common troubleshooting steps to diagnose and resolve the issue:

• Check for Additional Codes: Use an OBD-II scanner to check for any other related trouble codes. This can provide more context about the issue.
• Inspect the Wiring and Connectors: **Visual Inspection: Check the wiring harnesses and connectors related to the CAN bus for any signs of damage, corrosion, or loose connections.
• **Repair or Replace: If any damaged wires or connectors are found, repair or replace them as necessary.
• Test the CAN Bus: **Multimeter Test: Use a multimeter to check the voltage levels on the CAN High and CAN Low wires. The typical voltage levels should be around 2.5V when idle.
• **Scope Test: If available, use an oscilloscope to analyze the CAN signals for proper waveform and communication.
• Check for Short Circuits: Inspect the CAN bus wiring for any short circuits to ground or to other wires. This can cause communication failures.
• Inspect Modules: **Module Functionality: Check the functionality of the modules connected to the CAN bus. A malfunctioning module can disrupt communication.
• **Reprogram or Replace: If a specific module is identified as faulty, it may need to be reprogrammed or replaced.
• Check for Interference: Look for any aftermarket devices or modifications that may interfere with the CAN bus communication. This includes alarms, stereo systems, or other electronic devices.
• Battery and Ground Connections: Ensure that the vehicle’s battery is in good condition and that all ground connections are secure. Poor grounding can lead to communication issues.
• Clear Codes and Test Drive: After performing 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 CAN bus and U1705 code.
• Professional Diagnosis: If the issue persists after performing the above steps, consider seeking help from a professional mechanic or dealership with experience in diagnosing CAN bus issues. By following these steps, you should be able to identify and resolve the underlying cause of the U1705 code.