U1955 – Lost Communication with Body Control Module (BCM).

The ODBII code U1955 indicates a loss of communication between the vehicle’s control module and the Body Control Module (BCM), suggesting a potential issue with wiring, connectors, or the BCM itself.

The severity of ODBII code U1955 is generally considered moderate to high.

Common Causes For: U1954 U1954: Instrument Cluster Communication Failure

• Faulty Body Control Module (BCM)
• Damaged wiring or connectors
• Corroded terminals
• Poor ground connection
• Faulty communication network (CAN bus issues)
• Blown fuses
• Software or firmware issues in the BCM
• Intermittent electrical connections

Common misdiagnosis for U1955 Lost Communication with Body Control Module (BCM).

• Faulty Body Control Module (BCM)
• Wiring issues or damaged connectors
• Faulty or corroded ground connections
• Malfunctioning ignition switch
• Issues with the power supply to the BCM
• Other communication network failures (e.g., CAN bus issues)
• Faulty sensors or actuators connected to the BCM
• Software or firmware issues in the BCM

Common Troubleshooting Steps

When dealing with the OBD-II code U1955, which indicates “Lost Communication with Body Control Module (BCM),” 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. This can provide more context and help identify related issues.
• Inspect the Wiring and Connectors: **Visual Inspection: Check the wiring harness and connectors related to the BCM for any signs of damage, corrosion, or loose connections.
• **Connector Pins: Ensure that the pins in the connectors are not bent, corroded, or pushed back.
• Check Power and Ground: **Power Supply: Verify that the BCM is receiving the correct voltage. Use a multimeter to check the power supply to the BCM.
• **Ground Connections: Ensure that the ground connections for the BCM are secure and free of corrosion.
• Inspect the BCM: **Physical Condition: Check the BCM for any signs of physical damage or water intrusion.
• **Reprogramming: If the BCM has been replaced, ensure that it has been properly programmed to the vehicle.
• Test Communication Lines: **CAN Bus: Use a scan tool to check the communication on the CAN bus. If other modules are not communicating, there may be a fault in the bus itself.
• **Scope Testing: If available, use an oscilloscope to check for proper signal patterns on the communication lines.
• Check for Short Circuits: Inspect the wiring for any short circuits to ground or power that could affect communication with the BCM.
• Look for Intermittent Issues: If the code is intermittent, try to replicate the conditions under which the code appears. This could involve checking for specific vehicle conditions (e.g., temperature, humidity, etc.).
• Reset the Codes: Clear the trouble codes using the OBD-II scanner and see if the code returns. If it does, further investigation is needed.
• Consult Technical Service Bulletins (TSBs): Check for any TSBs related to the BCM or communication issues for your specific vehicle make and model. Manufacturers may have known fixes for common problems.
• 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.Conclusion Troubleshooting a U1955 code can be complex, as it often involves multiple systems and components. Following these steps systematically can help isolate the problem and lead to a resolution. Always ensure safety and proper procedures when working on vehicle electronics.