WOMS
U code network Medium severity

U1145 SCP (J1850) Invalid or Missing Data for Primary Id

The OBD2 code U1145 SCP (J1850) indicates that there is invalid or missing data for the primary identifier in the vehicle's communication network, which may affect the proper functioning of certain systems

Definition

The OBD2 code U1145 SCP (J1850) indicates that there is invalid or missing data for the primary identifier in the vehicle's communication network, which may affect the proper functioning of certain systems

Common causes

  • Faulty or damaged wiring/connectors
  • Malfunctioning control module
  • Poor ground connections
  • Communication issues between modules
  • Corrupted data or software glitches
  • Faulty sensors or actuators
  • Interference from aftermarket devices
  • Low battery voltage or power supply issues

Common misdiagnoses

  • Faulty vehicle speed sensor
  • Malfunctioning engine control module (ECM)
  • Wiring issues or short circuits
  • Faulty communication network (CAN bus)
  • Incorrectly configured or damaged diagnostic tools
  • Issues with other control modules (e.g., transmission control module)
  • Battery or power supply problems
  • Corrupted software or firmware in the vehicle's systems

Troubleshooting steps

  1. 1. Check for Other Codes

    Use an OBD-II scanner to check for any additional trouble codes. Addressing other codes may resolve the U1145 issue

  2. 2. Inspect the Wiring and Connectors

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

  3. 3. Repair or Replace

    Fix any damaged wiring or connectors that you find

  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 Modules

    Module Functionality: Verify that the primary module (often the PCM or another control module) is functioning correctly. If possible, use a scan tool to check for communication with the module

  6. 6. Module Replacement

    If a specific module is found to be faulty, consider replacing it

  7. 7. Inspect the SCP Bus

    Bus Integrity: Check the integrity of the SCP bus. Look for shorts, opens, or resistance issues in the wiring

  8. 8. Signal Testing

    Use an oscilloscope or multimeter to test the signal on the SCP bus for proper voltage levels and waveforms

  9. 9. Check for Interference

    Ensure that there are no aftermarket devices or modifications that could be interfering with the SCP communication

  10. 10. Perform a Network Test

    If available, use a professional scan tool to perform a network test to check the communication between modules on the SCP bus

  11. 11. Clear Codes and Test Drive

    After performing 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)

    Check for any TSBs related to the U1145 code for your specific vehicle make and model. Manufacturers may have specific fixes or recommendations

  13. 13. Seek Professional Help

    If the issue persists after performing the above steps, consider seeking help from a qualified technician or automotive professional who has experience with OBD-II systems and the specific vehicle. By following these troubleshooting steps, you should be able to identify and resolve the underlying issue causing the U1145 code