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U code network Medium severity

U1106 SCP (J1850) Invalid or Missing Data for Legislated Diagnostics

The OBD2 code U1106 SCP (J1850) Invalid or Missing Data for Legislated Diagnostics indicates that the vehicle's onboard diagnostic system has detected a communication issue or missing data related to legislated...

Definition

The OBD2 code U1106 SCP (J1850) Invalid or Missing Data for Legislated Diagnostics indicates that the vehicle's onboard diagnostic system has detected a communication issue or missing data related to legislated diagnostic functions, often due to a fault in the communication network or a malfunctioning module

Common causes

  • Faulty wiring or connectors in the SCP network
  • Malfunctioning or damaged control modules
  • Poor ground connections
  • Intermittent electrical issues
  • Corrupted data communication between modules
  • Software or firmware issues in the control modules
  • Faulty or disconnected sensors

Common misdiagnoses

  • Faulty OBDII connector
  • Bad ground connections
  • Malfunctioning PCM (Powertrain Control Module)
  • Corrupted software or firmware in the PCM
  • Wiring issues or shorts in the communication lines
  • Faulty sensors or actuators
  • Issues with the vehicle's battery or charging system
  • Intermittent communication faults
  • Problems with the vehicle's diagnostic system or tools
  • Incorrectly performed diagnostic procedures

Troubleshooting steps

  1. 1. Check for Additional Codes

    Use an OBD-II scanner to check for any other trouble codes that may be present. Addressing related codes can help in diagnosing the root cause

  2. 2. Inspect the Vehicle’s Wiring and Connectors

    Visual Inspection: Look for damaged, frayed, or corroded wiring and connectors related to the SCP (J1850) communication lines

  3. 3. Connector Integrity

    Ensure that all connectors are securely attached and free of dirt or corrosion

  4. 4. Test the SCP Communication Lines

    Use a multimeter or an oscilloscope to check the voltage levels and signal integrity on the SCP communication lines. Ensure that the signals are within the expected range

  5. 5. Check for Ground Issues

    Ensure that the ground connections for the modules involved in the SCP communication are secure and free of corrosion. Poor grounding can lead to communication issues

  6. 6. Inspect Modules for Functionality

    Identify the modules that communicate over the SCP bus (e.g., PCM, BCM, etc.) and check their functionality. A malfunctioning module can cause communication errors

  7. 7. If possible, perform a module reset or reprogramming if the manufacturer provides such procedures

  8. 8. Look for Software Updates

    Check if there are any software updates available for the vehicle’s modules. Sometimes, manufacturers release updates to fix known issues

  9. 9. Perform a Network Test

    If you have access to a professional-grade scan tool, perform a network test to see if all modules are communicating properly. This can help identify if a specific module is causing the issue

  10. 10. Check for Intermittent Issues

    If the code is intermittent, monitor the vehicle’s performance and check for conditions that may trigger the code, such as specific driving conditions or environmental factors

  11. 11. Clear the Code and Test Drive

    After performing the above checks and repairs, clear the code and take the vehicle for a test drive to see if the code returns

  12. 12. Consult Technical Service Bulletins (TSBs)

    Look for any TSBs related to the U1106 code for your specific vehicle make and model. Manufacturers may have documented common fixes for this issue.1

  13. 13. 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 your vehicle’s specific systems. By following these troubleshooting steps, you can systematically identify and resolve the underlying issue causing the U1106 code