U1175 – SCP (J1850) Invalid or Missing Data for Primary Id

The ODBII code U1175 SCP (J1850) indicates that there is invalid or missing data for the primary identifier in the communication network, typically related to a failure in data transmission between modules.

The severity of ODBII code U1175 is moderate.

Common Causes For: U1174 U1174: “Control Module Communication Fault”

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

Common misdiagnosis for U1175 SCP (J1850) Invalid or Missing Data for Primary Id

• Faulty vehicle speed sensor
• Malfunctioning engine control module (ECM)
• Wiring issues or short circuits
• Faulty communication network (CAN bus)
• Defective instrument cluster
• Bad ground connections
• Incorrectly configured aftermarket accessories
• Software glitches or updates needed in the ECM

Common Troubleshooting Steps

The OBD-II code U1175 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 control module is not receiving valid data from a primary module, which can lead to various performance issues. Here are some common troubleshooting steps to diagnose and resolve the U1175 code:

• Check for Other Codes: Use an OBD-II scanner to check for any additional trouble codes. Addressing other codes may resolve the U1175 issue.
• Inspect Wiring and Connectors: **Visual Inspection: Check the wiring and connectors related to the affected modules for any signs of damage, corrosion, or loose connections.
• **Repair or Replace: Repair any damaged wires or connectors as necessary.
• Check the SCP Bus: **Signal Integrity: Use a multimeter or oscilloscope to check the voltage levels on the SCP bus. Ensure that the signals are within the expected range.
• **Short Circuits: Look for any short circuits or open circuits in the wiring harness.
• Inspect Modules: **Module Functionality: Ensure that the primary module (often the PCM or another control module) is functioning correctly. If the module is faulty, it may need to be reprogrammed or replaced.
• **Ground Connections: Check the ground connections for the modules involved. Poor grounding can lead to communication issues.
• Check for Interference: **Electrical Interference: Look for any aftermarket devices or modifications that may be causing electrical interference on the SCP bus.
• Perform a Network Test: **Network Scan: Use a professional scan tool to perform a network test. This can help identify which module is not communicating properly.
• **Module Communication: Check if all modules on the SCP bus are communicating. If one module is not responding, it may be the source of the problem.
• Clear Codes and Test Drive: After performing the above checks and repairs, clear the trouble codes using the OBD-II scanner.
• Take the vehicle for a test drive to see if the code returns. Monitor the vehicle’s performance and any warning lights.
• Consult Technical Service Bulletins (TSBs): Check for any TSBs related to the U1175 code for your specific vehicle make and model. Manufacturers may have specific recommendations or known issues.
• Professional Diagnosis: If the issue persists after performing the above steps, consider seeking help from a professional mechanic or dealership. They may have access to advanced diagnostic tools and resources. By following these troubleshooting steps, you should be able to identify and resolve the issue causing the U1175 code.