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U1090SCP (J1850) Invalid or Missing Data for Non-Legislated Diagnostics

The OBD2 code U1090 SCP (J1850) Invalid or Missing Data for Non-Legislated Diagnostics indicates that the vehicle's communication network is not receiving valid data from a module, which may affect non-legislated...

Definition

The OBD2 code U1090 SCP (J1850) Invalid or Missing Data for Non-Legislated Diagnostics indicates that the vehicle's communication network is not receiving valid data from a module, which may affect non-legislated diagnostic functions

Common causes

  • Faulty or damaged wiring or connectors in the communication circuit
  • Malfunctioning control modules or sensors
  • Poor ground connections
  • Corrupted software or firmware in the control modules
  • Interference from aftermarket devices or modifications
  • Low battery voltage or weak battery
  • Faulty or disconnected communication bus (e.g., J1850 bus)

Common misdiagnoses

  • Faulty wiring or connectors
  • Defective control modules
  • Sensor malfunctions
  • Communication issues between modules
  • Battery or power supply problems
  • Software or firmware issues
  • Grounding problems
  • Incorrectly installed aftermarket accessories

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 other codes may resolve the U1090 issue

  2. 2.Inspect the Wiring and Connectors

    Visual Inspection: Look for damaged, corroded, or loose connectors and wiring related to the SCP bus

  3. 3.Connector Pins

    Ensure that the pins in the connectors are not bent or corroded

  4. 4.Check the Battery and Ground Connections

    Ensure that the battery is fully charged and that all ground connections are clean and secure. Poor ground connections can lead to communication issues

  5. 5.Test the SCP Bus

    Use a multimeter or an oscilloscope to check the voltage levels on the SCP bus. Compare the readings to the specifications in the vehicle’s service manual

  6. 6.Look for short circuits or open circuits in the wiring

  7. 7.Inspect Control Modules

    Check the control modules (e.g., PCM, BCM, ABS module) for any signs of damage or failure. If a specific module is suspected, it may need to be tested or replaced

  8. 8.Perform a Network Test

    If available, use a scan tool that can perform a network test to check the communication between modules. This can help identify which module is not responding

  9. 9.Check for Intermittent Issues

    Sometimes, communication issues can be intermittent. Pay attention to any patterns or specific conditions under which the code appears

  10. 10.Update Software/Firmware

    Check if there are any software updates available for the vehicle’s control modules. Sometimes, updating the software can resolve communication issues

  11. 11.Clear Codes and Test Drive

    After performing the above checks and repairs, clear the trouble codes 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 U1090 code for your specific vehicle make and model. Manufacturers may have specific fixes or recommendations.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 OBD-II systems and can perform more advanced diagnostics. By following these troubleshooting steps, you should be able to identify and resolve the underlying issue causing the U1090 code