U1105 – Lost Communication with Vehicle Anti-Theft System (VATS) Module.

The ODBII code U1105 indicates that there is a lost communication issue with the Vehicle Anti-Theft System (VATS) module, which may affect the vehicle’s security and starting functions.

The severity of ODBII code U1105 is moderate.

Common Causes For: U1104 SCP (J1850) Invalid or Missing Data for Chassis Status Request

• Faulty VATS module
• Damaged wiring or connectors
• Poor ground connection
• Blown fuse
• Malfunctioning ignition switch
• Corroded terminals
• Faulty key or key fob
• Issues with the vehicle’s PCM (Powertrain Control Module)

Common misdiagnosis for U1105 Lost Communication with Vehicle Anti-Theft System (VATS) Module.

• Faulty ignition switch
• Bad wiring or connectors
• Defective key or key fob
• Malfunctioning body control module (BCM)
• Issues with the engine control module (ECM)
• Battery or charging system problems
• Faulty anti-theft system components
• Incorrectly programmed or cloned keys
• Problems with the vehicle’s immobilizer system
• Software glitches in the vehicle’s computer systems

Common Troubleshooting Steps

When dealing with OBD-II code U1105, which indicates “Lost Communication with Vehicle Anti-Theft System (VATS) Module,” 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. Sometimes, multiple codes can provide more context for the issue.
• Inspect Wiring and Connectors: **Visual Inspection: Check the wiring and connectors related to the VATS module for any signs of damage, corrosion, or loose connections.
• **Connector Pins: Ensure that the pins in the connectors are not bent or corroded.
• Test the VATS Module: If accessible, test the VATS module for proper operation. This may involve checking the power and ground connections to the module.
• Use a multimeter to verify that the module is receiving the correct voltage.
• Check for Communication Issues: Use a scan tool to check if the VATS module is communicating with the vehicle’s network. If it is not, there may be a communication issue.
• Inspect the vehicle’s CAN (Controller Area Network) bus for faults. This may involve checking other modules for communication errors.
• Inspect the Fuses: Check the fuses related to the VATS system and the vehicle’s electrical system. A blown fuse can interrupt communication.
• Look for Interference: Ensure that there are no aftermarket devices or modifications that could interfere with the VATS system or its communication.
• Reset the System: Clear the trouble codes using the OBD-II scanner and see if the code returns. Sometimes, a temporary glitch can cause communication issues.
• Check the Ignition Switch: The ignition switch can sometimes cause issues with the VATS system. Ensure that it is functioning properly and making good contact.
• Consult Technical Service Bulletins (TSBs): Check for any TSBs related to the VATS system for your specific vehicle make and model. Manufacturers may have issued guidance on common issues.
• Professional Diagnosis: If the issue persists after performing the above steps, it may be necessary to consult a professional mechanic or dealership for further diagnosis. They may have specialized tools and knowledge to address complex issues.1
• Replace the VATS Module (if necessary): If all other troubleshooting steps have been exhausted and the VATS module is determined to be faulty, replacement may be necessary.Conclusion Always remember to take safety precautions when working on a vehicle’s electrical system. If you’re not comfortable performing these steps, it’s advisable to seek help from a qualified technician.