U1599 – Lost Communication with Vehicle Control Module.

The ODBII code U1599 indicates a loss of communication with a 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 U1599 is generally considered moderate to high.

Common Causes For: U1598 Lost Communication with the Hybrid Powertrain Control Module.

• Faulty Vehicle Control Module (VCM)
• Damaged wiring or connectors
• Poor ground connections
• Corroded terminals
• Faulty communication network (CAN bus issues)
• Software or firmware issues
• Battery or power supply problems
• Intermittent electrical connections

Common misdiagnosis for U1599 Lost Communication with Vehicle Control Module.

• Faulty Vehicle Control Module (VCM)
• Wiring issues or shorts in the communication lines
• Faulty connectors or terminals
• Issues with other control modules (e.g., ECM, BCM)
• Power supply problems to the control module
• Software or firmware issues in the control module
• Corrupted data or communication protocols
• Grounding issues in the electrical system

Common Troubleshooting Steps

The OBD-II code U1599 indicates a “Lost Communication with Vehicle Control Module.” This code typically suggests that there is a communication issue between the vehicle’s control modules, which can be caused by various factors. Here are some common troubleshooting steps to help diagnose and resolve the issue:

• Check for Additional Codes: Use an OBD-II scanner to check for any other trouble codes that may be present. 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 wiring harnesses that connect to the control modules.
• Check Power and Ground:
• Verify that the control module is receiving the proper power supply. Use a multimeter to check voltage at the module’s power and ground pins.
• Ensure that the ground connections are secure and free of corrosion.
• Test the Control Module:
• If possible, test the control module itself to ensure it is functioning correctly. This may involve using specialized diagnostic equipment or swapping the module with a known good one.
• 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, opens, or interference.
• Use an oscilloscope to monitor the CAN bus signals if you have access to one.
• Check for Software Updates:
• Sometimes, communication issues can be resolved with a software update. Check with the vehicle manufacturer for any available updates for the control modules.
• Clear Codes and Test Drive:
• After performing any repairs or inspections, 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):
• Look for any TSBs related to the specific make and model of the vehicle. Manufacturers may have issued guidance on known issues that could be relevant.
• Seek Professional Help:
• If the issue persists after performing the above steps, it may be necessary to consult a professional mechanic or dealership with experience in diagnosing complex communication issues. By following these troubleshooting steps, you can systematically identify and resolve the underlying cause of the U1599 code.