U2179 – Lost Communication with the Body Control Module (BCM) – Bus Off.

The ODBII code U2179 indicates a loss of communication with the Body Control Module (BCM) due to a “Bus Off” condition, meaning the BCM is not responding on the communication network, often due to a fault in the wiring, connectors, or the module itself.

The severity of ODBII code U2179 is generally considered moderate to severe.

Common Causes For: U2178 Lost Communication with the Hybrid Powertrain Control Module (HPCM) A.

• Faulty Body Control Module (BCM)
• Damaged wiring or connectors in the communication circuit
• Faulty or damaged CAN bus
• Poor ground connections
• Short circuits in the wiring
• Corroded connectors
• Intermittent electrical issues
• Malfunctioning other modules on the CAN bus
• Software issues or programming errors in the BCM
• Battery or power supply issues affecting the BCM

Common misdiagnosis for U2179 Lost Communication with the Body Control Module (BCM) – Bus Off.

• Faulty Body Control Module (BCM)
• Wiring issues or damaged connectors
• Faulty Instrument Cluster
• Power supply issues
• Faulty CAN bus communication lines
• Faulty or corroded ground connections
• Issues with other control modules
• Software or firmware issues in the BCM or other modules

Common Troubleshooting Steps

When dealing with OBD-II code U2179, which indicates “Lost Communication with the Body Control Module (BCM) – Bus Off,” 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 the BCM: **Power and Ground: Verify that the BCM is receiving proper power and ground. Use a multimeter to check voltage at the BCM connector.
• **Functionality: If possible, test the BCM in another vehicle or replace it with a known good unit to see if the problem persists.
• Inspect the CAN Bus: **Bus Communication: The U2179 code often relates to issues with the Controller Area Network (CAN) bus. Check for proper communication between the BCM and other modules.
• **Termination Resistors: Ensure that the CAN bus has the correct termination resistors in place and that they are functioning properly.
• Check for Short Circuits or Open Circuits: Use a multimeter to check for shorts or opens in the wiring that connects the BCM to other modules and the CAN bus.
• Scan for Communication Issues: Use a professional scan tool to monitor live data and check for communication between the BCM and other modules. Look for any modules that are not responding.
• Inspect for Environmental Factors: Check for moisture or water intrusion in the BCM area, as this can cause communication issues. Look for signs of rust or corrosion.
• Reset the System: After performing checks and repairs, clear the codes using the OBD-II scanner and see if the code returns after a test drive.
• Consult Technical Service Bulletins (TSBs): Look for any TSBs related to the specific make and model of the vehicle, as manufacturers may have issued guidance on common issues related to the BCM.
• Seek Professional Help: If the issue persists after performing these steps, it may be necessary to consult a professional mechanic or automotive technician who has experience with the specific vehicle and its systems. By following these steps, you should be able to identify the root cause of the U2179 code and take appropriate action to resolve the communication issue with the Body Control Module.