U1199 – Lost Communication with Vehicle Control Module.

The ODBII code U1199 indicates a loss of communication with the vehicle control module, suggesting that the module is not responding or is unable to communicate with other systems in the vehicle.

The severity of ODBII code U1199 is generally considered moderate to severe.

Common Causes For: U1198 U1198: “Module Communication Failure”

• Faulty Vehicle Control Module (VCM)
• Damaged wiring or connectors
• Poor ground connections
• Corrupted software or firmware
• Faulty communication network (CAN bus issues)
• Blown fuses
• Intermittent electrical connections
• Malfunctioning sensors or actuators

Common misdiagnosis for U1199 Lost Communication with Vehicle Control Module.

• Faulty wiring or connectors
• Defective vehicle control module (VCM)
• Malfunctioning body control module (BCM)
• Issues with the powertrain control module (PCM)
• Problems with the instrument cluster
• Faulty sensors or actuators
• Battery or charging system issues
• Software or firmware glitches
• Communication network problems (CAN bus issues)
• Grounding issues

Common Troubleshooting Steps

The OBD-II code U1199 indicates a “Lost Communication with Vehicle Control Module.” This code typically suggests that there is a communication issue between the vehicle’s control modules. Here are some common troubleshooting steps to help diagnose and resolve the issue:

• Check for Other Codes: Use an OBD-II scanner to check for any other trouble codes that may be present. Sometimes, other codes can provide additional context for the communication issue.
• Inspect Wiring and Connectors:
• Visually inspect the wiring and connectors associated with the affected control module. 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 control module is receiving the proper voltage. Use a multimeter to check the power supply to the module.
• Verify that the fuses related to the control module are intact and functioning.
• Test the Control Module:
• If possible, test the control module itself. This may involve using a scan tool to communicate with the module or swapping it with a known good module if available.
• Some vehicles may require specific procedures to reset or reprogram the control module.
• Inspect the CAN Bus:
• The communication between control modules often occurs over a Controller Area Network (CAN) bus. Check for any issues with the CAN bus wiring, such as shorts or opens.
• Use an oscilloscope or a CAN bus diagnostic tool to monitor the bus for proper communication signals.
• Check for Interference:
• Look for any aftermarket devices or modifications that may interfere with the vehicle’s communication systems. This includes alarm systems, stereo systems, or other electronic accessories.
• Perform a Network Test:
• Some advanced scan tools can perform a network test to check the communication between modules. This can help identify which module is not communicating properly.
• 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 reappears.
• Consult Technical Service Bulletins (TSBs):
• Check for any manufacturer-specific TSBs related to the U1199 code or communication issues. There may be known fixes or updates available.
• Seek Professional Help:
• If the issue persists after performing these steps, it may be necessary to consult a professional mechanic or technician who has experience with the specific make and model of the vehicle. By following these troubleshooting steps, you can systematically identify and resolve the communication issue associated with the U1199 code.