U1959 – Lost Communication with Body Control Module (BCM).

The ODBII code U1959 indicates that there is a communication failure between the vehicle’s control modules and the Body Control Module (BCM), which may affect various electrical functions and systems in the vehicle.

The severity of ODBII code U1959 is generally considered moderate to severe, as it indicates a communication issue that can affect various vehicle functions.

Common Causes For: U1957 Lost Communication with the Instrument Cluster.

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

Common misdiagnosis for U1959 Lost Communication with Body Control Module (BCM)”.

• Faulty Body Control Module (BCM)
• Wiring issues or shorts in the communication lines
• Faulty or corroded connectors
• Issues with the power supply to the BCM
• Problems with other control modules
• Software or firmware issues in the BCM
• Faulty ignition switch
• Battery or charging system problems
• Grounding issues
• Faulty sensors or actuators related to the BCM

Common Troubleshooting Steps

When dealing with the OBD-II code U1959, 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 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 Wiring and Connectors: **Visual Inspection: Check the wiring harness and connectors leading 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 at the BCM connector.
• **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, the issue may be with the bus itself.
• **Scope Testing: If available, use an oscilloscope to check for proper signal patterns on the communication lines.
• Check for Intermittent Issues: **Temperature Sensitivity: Sometimes, issues can be temperature-related. Check if the problem occurs only under certain conditions (e.g., after the vehicle has been running for a while).
• **Vibration: Look for issues that may arise from vibration or movement, which could affect connections.
• Inspect Related Modules: If the BCM is not communicating, check other modules that may be connected to the same communication lines. A fault in one module can affect communication with others.
• Perform a Hard Reset: Disconnect the vehicle’s battery for a few minutes to reset the BCM and other modules. Reconnect and see if the code reappears.
• Consult Technical Service Bulletins (TSBs): Check for any manufacturer-specific TSBs related to the U1959 code or BCM issues. There may be known fixes or recalls.
• Replace the BCM (if necessary): If all other troubleshooting steps fail and the BCM is determined to be faulty, consider replacing it. Ensure proper programming and configuration after replacement.1
• Seek Professional Help: If you are unable to resolve the issue, it may be best to consult a professional mechanic or automotive technician who has experience with your specific vehicle make and model. By following these steps, you should be able to identify the root cause of the U1959 code and take appropriate action to resolve the communication issue with the Body Control Module.