U1224 – SCP (J1850) Invalid or Missing Data for Primary Id

The ODBII code U1224 indicates that the vehicle’s communication network is receiving invalid or missing data from the primary identifier, which is part of the SCP (Serial Communication Protocol) used in J1850 systems.

The severity of ODBII code U1224 is moderate.

Common Causes For: U1223 U1223: Instrument Cluster Communication Failure

• Faulty or damaged wiring/connectors
• Malfunctioning control modules
• Poor ground connections
• Communication network issues
• Corrupted data signals
• Incompatible or faulty aftermarket devices
• Software glitches in the vehicle’s systems
• Low battery voltage or power supply issues

Common misdiagnosis for U1224 SCP (J1850) Invalid or Missing Data for Primary Id

• Faulty ABS module
• Malfunctioning PCM (Powertrain Control Module)
• Defective wiring or connectors
• Bad ground connections
• Issues with the instrument cluster
• Faulty communication lines
• Incorrectly programmed or updated software
• Problems with the body control module (BCM)

Common Troubleshooting Steps

The OBD-II code U1224 indicates that there is an issue with the communication on the SCP (Serial Communication Protocol) bus, specifically related to the J1850 protocol. This code typically means that the vehicle’s onboard computer is not receiving valid data from a module that it expects to communicate with. Here are some common troubleshooting steps to diagnose and resolve the issue:

• Check for Other Codes: Use an OBD-II scanner to check for any other trouble codes that may be present. Addressing other codes may resolve the U1224 code.
• Inspect Wiring and Connectors: Visually inspect the wiring and connectors associated with the affected modules. Look for signs of damage, corrosion, or loose connections.
• Pay special attention to the connectors for the modules that are part of the SCP network.
• Check the Battery and Ground Connections: Ensure that the vehicle’s battery is fully charged and that all ground connections are clean and secure. Poor ground connections can lead to communication issues.
• Test the Modules: Identify the modules that are part of the SCP network. Use a scan tool to check if they are communicating properly.
• If a specific module is not responding, it may be faulty and require replacement.
• Check for Short Circuits or Open Circuits: Use a multimeter to check for short circuits or open circuits in the wiring harness associated with the SCP network.
• Ensure that the wiring is intact and that there are no breaks or shorts.
• Inspect the SCP Bus: If possible, use an oscilloscope to monitor the SCP bus for proper signal levels and communication patterns.
• Look for any irregularities in the signal that could indicate a problem.
• Update or Reprogram Modules: In some cases, a software update or reprogramming of the affected modules may be necessary. Check with the manufacturer for any available updates.
• Clear Codes and Test Drive: After performing any repairs or adjustments, clear the trouble codes and take the vehicle for a test drive to see if the U1224 code returns.
• Consult Technical Service Bulletins (TSBs): Check for any TSBs related to the U1224 code for your specific vehicle make and model. Manufacturers may have specific recommendations or known issues.
• Seek Professional Help: If the issue persists after performing the above steps, it may be necessary to consult a professional mechanic or technician who has experience with OBD-II systems and the specific vehicle in question. By following these troubleshooting steps, you should be able to identify and resolve the issue causing the U1224 code.