U1660 – Lost Communication with Body Control Module (BCM).

The ODBII code U1660 indicates a loss of communication between the vehicle’s control module and the Body Control Module (BCM), which can affect various electrical systems and functions.

The severity of ODBII code U1660 is generally considered moderate to severe.

Common Causes For: U1659 Lost Communication with Instrument Panel Cluster (IPC) Control Module.

• 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 U1660 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 Powertrain Control Module (PCM)
• Malfunctioning Instrument Cluster
• Battery or charging system problems
• Faulty sensors or actuators related to the BCM
• Software or firmware issues in the BCM or other modules

Common Troubleshooting Steps

When dealing with the OBD-II code U1660, 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 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 Environmental Factors: Check for any environmental factors that could affect the BCM, such as moisture or extreme temperatures.
• 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): Look for any TSBs related to the U1660 code for your specific vehicle make and model. Manufacturers may have known fixes or updates.
• Replace the BCM (if necessary): If all other 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 vehicle’s make and model. By following these steps, you should be able to identify the cause of the U1660 code and take appropriate action to resolve the communication issue with the Body Control Module.