U1905 – BCM Communication Failure

The ODBII code U1905 indicates a communication failure between the Body Control Module (BCM) and other modules in the vehicle’s network, suggesting a problem with data exchange or connectivity.

The severity of ODBII code U1905 is moderate.

Common Causes For: U1904 U1904: “BCM Communication Failure”

• Faulty Body Control Module (BCM)
• Damaged wiring or connectors
• Poor ground connections
• Corroded terminals
• Communication network issues (CAN bus problems)
• Software glitches or programming errors
• Malfunctioning related modules (e.g., PCM, ABS)
• Low battery voltage or power supply issues

Common misdiagnosis for U1905 U1905: “BCM Communication Failure”

• Faulty Body Control Module (BCM)
• Wiring issues or shorts in the communication lines
• Defective or corroded connectors
• Malfunctioning other control modules (e.g., PCM, ABS)
• Battery or power supply issues
• Software or firmware glitches
• Grounding problems
• Intermittent faults in the CAN bus system

Common Troubleshooting Steps

The OBD-II code U1905 indicates a “BCM Communication Failure,” which typically means there is a problem with the communication between the Body Control Module (BCM) and other 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. Other codes may provide more context or indicate related issues.
• Inspect Wiring and Connectors:
• Visually inspect the wiring and connectors associated with the BCM and other modules. Look for signs of damage, corrosion, or loose connections.
• Pay special attention to the ground connections, as poor grounding can lead to communication issues.
• Check Power Supply:
• Ensure that the BCM is receiving the correct voltage. Use a multimeter to check the power supply to the BCM.
• Verify that the fuses related to the BCM and communication circuits are intact.
• Test the BCM:
• If possible, perform a self-test of the BCM using a scan tool. Some scan tools can communicate with the BCM to check for internal faults.
• If the BCM is not responding, it may need to be replaced.
• Inspect Other Modules:
• Check the other modules that communicate with the BCM (e.g., ABS, PCM, etc.) for faults. A malfunctioning module can disrupt communication.
• Ensure that all modules are properly connected and functioning.
• Check for Software Updates:
• Some vehicles may require software updates for the BCM or other modules. Check with the manufacturer or a dealership for any available updates.
• 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 Technical Service Bulletins (TSBs):
• Look for any TSBs related to the U1905 code for your specific vehicle make and model. Manufacturers may have specific recommendations or known issues.
• Professional Diagnosis:
• If the issue persists after performing the above steps, consider seeking help from a professional mechanic or dealership. They may have specialized tools and knowledge to diagnose complex communication issues. By following these steps, you can systematically identify and resolve the underlying cause of the U1905 code.